Jenst

Add a short note about the latest changes in the current post or page.
WP Update message adds a metabox in admin post or page section. If you updated a post or page with important information you can write a note about it here.
There are a few optional settings, but the plugin works fine even without changing anything.
<h4>Settings</h4>
You can choose a style theme and more.
<ul>
<li>Published date format (if published date should be included)</li>
<li>Updated date format (if updated date should be included)</li>
<li>Position</li>
<li>HTML</li>
<li>New row replacement</li>
<li>Style theme</li>
</ul>

WP Update Message

Add a short note about the latest changes in the current post or page.

DefProc

TweetUpdater will send a message to your Twitter account, from you WordPress installation, whenever a new post is published, or when a previously published 
post is updated; as you choose.
The tweet format is flexible, with placeholders for title and URL. URLs can be included from a variety of sources. In addition to full 
post permalinks (standard or friendly urls as selected in your site setup) the following short url services are supported:
Internal services:
<ul>
<li><a href="https://wordpress.org/extend/plugins/le-petite-url/" rel="ugc">la petite url</a> plugin</li>
<li>WordPress Permalink</li>
</ul>
Generic shorteners
<ul>
<li>YOURLS</li>
</ul>
External services:
<ul>
<li>Bit.ly</li>
<li>Stwnsh</li>
<li>TinyURL</li>
</ul>
Posts tweeting can be ommited based on post category, or custom field, or custom field and value pair.
Derived from the original TwitterUpdater, version 3 has been fully rewritten to include OAuth authorisation with Twitter; because basic 
authentication (username & password) has now been deactivated for applications using the Twitter API.
The TwitterUpdater plugin has a great tradition of being updated and improved by anyone who needed it to do something different, and 
as such TweetUpdater is one of a handful of TwitterUpdater forks.
If the short url service you like to use is not included, please see the FAQ on how to add it. If you add a service, let me know and 
I’ll add the code to the next release.
<ul>
<li>Support & Bug reports at <a href="http://github.com/DefProc/TweetUpdater/issues" rel="nofollow ugc">github.com/DefProc/TweetUpdater/issues</a></li>
</ul>

TweetUpdater

Send messages to Twitter when a post is published or updated; uses OAuth. Will add a short URL from a plugin, or from an external service.

WP Update Message vs TweetUpdater