Update - Hulu today finally announced its Hulu Plus service that was originally scheduled to debut last month.
The service is priced at the $9.99 / month that was widely reported in pre-announcement press. A slight surprise is support for Apple iPhones running iOS4 (4, 3GS), Wi-fi and 3G iPads and 3rd Generation only (running iOS4) iPod Touches.
In addition to support on any computer with IE, Firefox, Safari 3.0 or Chrome, and Flash Player 10.0.22 or above, the service launches with support for select Samsung Internet-enabled TVs and Blu-ray players. Support for Sony's PS3 is shown as "Coming Soon", Microsoft's Xbox 360 as "Coming Early 2011" and Sony and Vizio TVs and Blu-ray players "Coming Fall 2010".
It's hard to tell whether your $10 a month buys you all episodes of all seasons of all shows in Hulu's catalog. There's a "Current Season Ticket" option shown for 33 popular shows. The "Watch Past Seasons" teaser also shows 33 shows (I didn't cross check them with the Current Season list). But my guess is that Hulu isn't offering all seasons of every show it carries.
Bloomberg BusinessWeek reports: "The company also is in talks to add shows from CBS Corp., Viacom Inc. and Time Warner Inc. to the websites subscription service, people with direct knowledge of the discussions said".
Hulu will continue its free website service in addition to the Plus service.
If you're interested, hop on over to Hulu and request an invite.
Update 1: The iPad Hulu+ app provides access to some sample content. The bad news is that it includes commercials just like those on the free Hulu service. So you're paying for access to a deeper catalog, but not freedom from ads!
Update 2: More about Plus on Hulu's Blog post.