Popular desktop Twitter client Twhirl has a new sibling. Seesmic CEO Loic Le Meur, who acquired the Adobe AIR-based application about a year ago, has dubbed the new service “Seesmic Desktop,” which is being launched in preview as a separate product from Twhirl.

Some of the new features include the capability to monitor multiple feeds side-by-side in a similar fashion to TweetDeck, create custom user lists, and post from multiple accounts while the application keeps track of which ones are which to keep duplicates at bay. You can also drag and drop photos from your computer to post straight to Twitter, making use of the fact that it’s running off of Adobe’s AIR platform.

However, not all of this functionality will be available from the get-go. The service is being launched in “preview” and will support only Twitter, however Le Meur said his team is on track to release support for other services in about a month. He also said that there’s a pro version on the way that should fill in the company’s business model, since this version–just like Twhirl, will not contain advertising.

One thing is clear though–Twhirl’s life cycle may be at an end. While Le Meur said that development will continue on it, that could simply mean bug fixes. Considering Seesmic Desktop is launching as a Twitter client from the get-go should tell you something.

Seesmic Desktop preview is available for download right now, although you’ve got to sign up to be a member of “Team Seesmic,” the company’s new community site.

You can catch the whole live blog after the break.

The new Seesmic Desktop is kind of like the old Twhirl, meets Tweetdeck–with a dash of iTunes.

(Credit: CNET Networks)

Seesmic Desktop launch