copperblade

Update: If you need more functionality please see the next generation of this plugin at https://wordpress.org/extend/plugins/network-latest-posts/
Creates a widget to show a list of the most recent posts across a WordPress MU installation. It shows the most recent post from each blog. This plugin is based on the work of many authors.
This works on previous versions of WPMU, but not on previous versions of WordPress (where it doesn’t make sense).
<h3>Options</h3>
<ul>
<li>Number of posts to show – list this many posts.</li>
<li>Number of days to limit – only go back this number of days to get posts. Set to -1 for no limit (default).</li>
</ul>

Multisite Recent Posts Widget

Creates a widget to show a list of the most recent posts across a WordPress MU installation.  It shows the most recent post from each blog.

feedmeastraycat

WordPress removes the Update Services ability (Settings – Writing) when you create a network (aka enables WordPress MU/Multisite). 
Activate this plugin to get it back.
Note: This is only for WordPress setups with a network, aka multiple sites, aka multisites, 
aka WPMU in WordPress 3 and later.
This plugin might work with older WordPress MU sites. I haven’t tested it though. If you do, please 
let me know how it turned out.
<h3>Files</h3>
<ul>
<li>/activate-update-services/activate-update-services.php</li>
<li>/activate-update-services/README.txt</li>
</ul>

Activate Update Services

WordPress removes the Update Services ability when you create a network. Activate this plugin to get it back.

Multisite Recent Posts Widget vs Activate Update Services