Marco Buttarini

wg-twitter-widget is THE widget to show twitter status in wordpress sidebar. 
Developed starting from the existing widget of Sarah Isaacson, * using the example widget of Justin Tadlock

WG Twitter Widget

Twitter Widget Highly configurable, with image and last twit of users

H. Peter Pfeufer

This Plugin will add a twitter timelina as a sidebarwidget to your wordpress-blog. This timeline is provided by twitter as you can see <a href="http://twitter.com/about/resources/widgets/widget_profile" rel="nofollow ugc">here</a>. 
Now you dont need to copy and paste the code from twitter with your settings anymore, just install the plugin and set the options.
Features
<ul>
<li>Easy install</li>
<li>Panel for easy configuration</li>
<li>Customisation via CSS in settings</li>
</ul>
Available Languages
<ul>
<li>English</li>
<li>German</li>
</ul>

WP Twitter Timeline

Add a sidebarwidget with your twitter timeline to your WordPress-Blog.

WG Twitter Widget vs WP Twitter Timeline