Speedboxer

This plugin will convert valid <a href="http://twitter.com/" title="Twitter" rel="nofollow ugc">Twitter</a> usernames mentioned in comments into a link to their Twitter profile page. For example, if somebody mentions “@mattfreedman” in their comment, this plugin will check with Twitter to see if the user “mattfreedman” exists (which is does) and when it does, it will convert it into “<a href="http://twitter.com/mattfreedman" rel="nofollow ugc">@mattfreedman</a>“.
Please note: As this plugin converts usernames on the fly (whenever and everytime somebody views the comments), and checks Twitter for every username (to ensure it’s valid), I strongly recommend using a caching plugin such as <a href="https://wordpress.org/extend/plugins/wp-super-cache/" title="WP Super Cache" rel="ugc">WP Super Cache</a>. Which will not only lessen the load on Twitter’s servers, but also speed up page loads.
Although it says this plugin requires WordPress 2.6, I see no reason why it wouldn’t work with earlier versions, I just haven’t tested it with earlier version.
This plugin requires cURL to be installed on your server, and has only been tested with PHP 5.2.x.

Twitter Links

Converts Twitter usernames mentioned in comments (eg. @mattfreedman) with a link to the mentioned user's Twitter profile page.

Ben Balter

Twitter Mentions as Comments does exactly what it promises to do – scours Twitter for people talking about your blog posts and silently inserts their Tweets alongside your existing comments. The plugin leverages the power of WordPress’s built-in commenting system – notification, comment moderation, author white/black listing – making Twitter an extension of your blog.
<h4>Features</h4>
<ul>
<li>Searches for Tweets linking to your blog posts, regardless of the URL shortener used (using Twitter’s Search API)</li>
<li>Pushes Tweets into WordPress’s existing comment workflow – notifications, comment moderation, and author whitelists/blacklists work just like any other comment</li>
<li>Fetches user’s real name and profile picture and links directly to the original Tweet</li>
<li>Checks automatically – no need to do a thing</li>
<li>Option to automatically exclude ReTweets</li>
<li>Option to store tweets as trackbacks/pingbacks</li>
<li>Option to specify which posts to check (e.g., 10 most recent posts, all posts, front page only)</li>
<li>Smart Caching of Tweets and user data – retrieves only what it needs to save on API calls and server load</li>
</ul>
<h4>Planned Features</h4>
<ul>
<li>Dynamic resizing of Twitter profile images to fit WordPress theme</li>
<li>Prioritization of newer posts</li>
<li>Oauth Authentication to raise API limit (currently unlimited Tweets, but limited to 150 new comment authors per hour)</li>
<li>Smarter API throttling</li>
</ul>
You can see it in action on the <a href="http://ben.balter.com/2010/09/12/wordpress-resume-plugin/#comment-168" rel="nofollow ugc">WP Resume Plugin page</a>.
Questions? Comments? Feature Requests? Have a great idea? Please see <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/wiki/Where-to-get-Support-or-Report-an-Issue" rel="nofollow ugc">where to get support or report an issue</a> and <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/wiki/How-to-Contribute" rel="nofollow ugc">how to contribute</a>.
Developers, have a killer feature you’d love to see included? Feel free to <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/" rel="nofollow ugc">fork the project on GitHub</a> and submit your contributions via pull request.
Enjoy using Twitter Mentions as Comments? Feel free to <a href="http://ben.balter.com/donate/" rel="nofollow ugc">make a small donation</a> to support the software’s continued development.
[Photo via <a href="http://www.flickr.com/photos/joshsemans/3414271359/" rel="nofollow ugc">joshsemans</a>]
<h3>Donate</h3>
Enjoy using Twitter Mentions as Comments? Please consider <a href="http://ben.balter.com/donate/?utm_source=wiki&utm_medium=donate&utm_campaign=tmac" rel="nofollow ugc">making a small donation</a> to support the project’s continued development.
<h3>How To Contribute</h3>
Twitter Mentions as Comments is an open source project and is supported by the efforts of an entire community. We’d love for you to get involved. Whatever your level of skill or however much time you can give, your contribution is greatly appreciated.
<ul>
<li>Everyone – help expand the projects <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/wiki" rel="nofollow ugc">documentation wiki</a> to make it easier for other users to get started</li>
<li>Users – download the latest <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/tree/develop" rel="nofollow ugc">development version</a> of the plugin, and <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/issues" rel="nofollow ugc">submit bug/feature requests</a>.</li>
<li>Non-English Speaking Users – <a href="http://translations.benbalter.com/projects/Twitter-Mentions-as-Comments/" rel="nofollow ugc">Contribute a translation</a> using the GlotPress web interface – no technical knowledge required (<a href="http://translations.benbalter.com/projects/how-to-translate" rel="nofollow ugc">how to</a>).</li>
<li>Developers – <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/tree/develop" rel="nofollow ugc">Fork the development version</a> and submit a pull request, especially for any <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/issues?direction=desc&sort=created&state=open" rel="nofollow ugc">known issues</a></li>
</ul>
<h3>Where To Get Support Or Report An Issue</h3>
There are various resources available, depending on the type of help you’re looking for:
<ul>
<li>
For getting started and general documentation, please browse, and feel free to contribute to <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/wiki" rel="nofollow ugc">the project wiki</a>.
</li>
<li>
For support questions (“How do I”, “I can’t seem to”, etc.) please search and if not already answered, open a thread in the <a href="https://wordpress.org/support/plugin/Twitter-Mentions-as-Comments" rel="ugc">Support Forums</a>.
</li>
<li>
For technical issues (e.g., to submit a bug or feature request) please search and if not already filed, <a href="https://github.com/benbalter/Twitter-Mentions-as-Comments/issues" rel="nofollow ugc">open an issue on GitHub</a>.
</li>
<li>
For implementation, and all general questions (“Is it possible to..”, “Has anyone…”), please search, and if not already answered, post a topic to the <a href="https://groups.google.com/forum/#!forum/Twitter-Mentions-as-Comments" rel="nofollow ugc">general discussion list serve</a>
</li>
</ul>

Twitter Mentions As Comments

Twitter Mentions as Comments scours Twitter for people talking about your site & silently inserts their Tweets alongside your existing comments.

Twitter Links vs Twitter Mentions As Comments