This is the Vikinghammer Tweet plugin.
You can set it up to post tweets based on new posts or comments to your blog. This requires that you enter your Twitter credentials.

Vikinghammer Tweet

Send a tweet for any new post or comment to your blog.

RobMarsh

Recent Comments displays a list of your blog’s newest comments. The output can be customised in <a href="http://rmarsh.com/plugins/post-options/" rel="nofollow ugc">many</a> ways.
This plugin requires the latest version of the Post-Plugin Library: <a href="https://downloads.wordpress.org/plugin/post-plugin-library.zip" rel="nofollow ugc">download it now</a>.
<h3>Version History</h3>
<ul>
<li>2.6.2.1
<ul>
<li>option (‘unique’) to only show one comment per post</li>
</ul>
</li>
<li>2.6.2.0
<ul>
<li>new {imagealt} output tag — rather like {imagesrc}</li>
<li>{excerpt} can now trim to whole sentences</li>
<li>content filter can now take parameter string</li>
<li>widget can now take parameter string</li>
<li>output can be appended to posts & feeds</li>
</ul>
</li>
<li>2.6.1.0
<ul>
<li>the current post can be marked manually</li>
<li>widgets now honour the option to show no output if list is empty</li>
</ul>
</li>
<li>2.6.0.1
<ul>
<li>bug fix: installation code was failing on some systems</li>
</ul>
</li>
<li>2.6.0.0
<ul>
<li>version bump to indicate compatibility with WP 2.6</li>
<li>fix to really include attachments</li>
<li>new parameter for {imagesrc} to append a suffix to the image name, e.g. to get the thumbnail for attachments</li>
</ul>
</li>
<li>2.5.0.11
<ul>
<li>new option to include attachments</li>
<li>{php} tag now accepts nested tags</li>
<li>new output tag {authorurl} — permalink to archive of author’s posts</li>
</ul>
</li>
<li>2.5.0.10
<ul>
<li>fix for page selection in old versions of WP</li>
<li>made omit current post try harder to find current post ID</li>
</ul>
</li>
<li>2.5.0.9
<ul>
<li>new option to match the current post’s author</li>
<li>extended options for snippet and excerpt output tags</li>
</ul>
</li>
<li>2.5.0.7
<ul>
<li>new option to show by status, i.e., published/private/draft/future</li>
<li>{categorynames} and {categorylinks} apply ‘single_cat_name’ filter</li>
<li>fixes bug in WP pre-2.2 causing installation to fail</li>
</ul>
</li>
<li>2.5.0.1
<ul>
<li>new option to only show comments for the current post</li>
</ul>
</li>
<li>2.5.0
<ul>
<li>{image} has new post, link, and default parameters</li>
<li>new {imagesrc} tag</li>
<li>fix to empty category bug</li>
<li>excluded posts bug fix</li>
<li>fix for intermittent bug with ‘omit current post’ option</li>
</ul>
</li>
<li>2.5b26
<ul>
<li>reverted thumbnail serving (speed)</li>
<li>fix current post after extra query</li>
</ul>
</li>
<li>2.5b25
<ul>
<li>option to sort output, group templates</li>
<li>removed ‘trim_before’ option added more logical ‘divider’</li>
<li>{date:raw}, {commentdate:raw}, etc.</li>
<li>fix for {image} resizing when and not </li>
<li>{image} now serves real thumbnails</li>
</ul>
</li>
<li>2.5b24
<ul>
<li>fix for recursive replacement by content filter</li>
<li>fix to {gravatar} to allow for ‘identicon’ etc.</li>
<li>fix to {commenter} to allow trimming</li>
<li>fix a warning in safe mode</li>
</ul>
</li>
<li>2.5b23
<ul>
<li>new option to filter on custom fields</li>
<li>nested braces in {if}; condition now taggable</li>
<li>improved bug report feature</li>
<li>better way to omit user comments</li>
</ul>
</li>
<li>2.5b22
<ul>
<li>fixes for tag bugs</li>
<li>show_pages option can now show only pages</li>
<li>omit registered user comments option added</li>
</ul>
</li>
<li>2.5b19
<ul>
<li>fix for content replacement filter</li>
</ul>
</li>
<li>2.5b18
<ul>
<li>fix output filter bug</li>
<li>add conditional tag {if:condition:yes:no}</li>
</ul>
</li>
<li>2.5b16
<ul>
<li>fix for {php}</li>
</ul>
</li>
<li>2.5b15
<ul>
<li>fix bugs, add ‘included posts’ setting</li>
</ul>
</li>
<li>2.5b14
<ul>
<li>fix file-encoding, installation error, etc.</li>
</ul>
</li>
<li>2.5b11
<ul>
<li>some widget fixes</li>
</ul>
</li>
<li>
2.5b9
<ul>
<li>clarifying installation instructions</li>
</ul>
</li>
<li>
<a href="http://rmarsh.com/plugins/recent-comments/" rel="nofollow ugc">previous versions</a>
</li>
</ul>

Vikinghammer Tweet vs Recent Comments