Hi
This is the Yedda blog page that explains it:
http://blog.yedda.com/?p=143
"One of the things we like to work on in Yedda, is letting you use Yedda wherever you want to across the internet. You can already use the Yedda widgets, Yedda’s Twitter integration, Yedda’s Facebook application or our custom Feedflares, but that just wasn’t enough.
We figure that the best way to have Yedda always accessible is to make a toolbar, so here it is:
The new toolbar allows easy access to Yedda right from your browser along with some cool new features. And like everything else on Yedda, it’s totally free and doesn’t spy on you or contain pop-ads (here’s the privacy statement). Get it now!"