Seesmic Desktop packs TweetDeck's features with a smaller footprint
Yes, it's also an Adobe Air app. Unlike the relatively inobtrusive Thwirl, however, Desktop offers a customizable, multi-paned display that allows you to simultaneously view different bits of Twitter's bottomless supply of data - your @replies, direct messages, searches, and more.
The interface is clean, though possibly a bit too "Mac" for some users. Color schemes aren't easily adjustable (yet), though there are 15 XML config files in the "color schemes" folder. Links can be shortened using six different services - including Digg, and inline uploading of images to TwitPic is also available.
Seesmic Desktop doesn't have TweetDeck's voracious appetite for RAM. At startup it weighed in at about 65Mb and has reached 79Mb after letting it run overnight. Leaving TweetDeck on would typically result in anywhere between 300 and 600Mb of memory consumed. Seesmic also supports multiple Twitter accounts, so it bests TweetDeck beaten on two fronts.
But wait, where's the Facebook support? When Seesmic released their Air-based client for FB last month, they told us a unified client was coming. Seesmic Desktop is likely it, but since it's still a preview we'll have to wait and see what other features are added in upcoming releases. Right now, though, Seesmic Desktop definitely shows promise.