Thanks to Jeebs over at SpoilerTV for this info. You can see Amazon's page for S3 DVD HERE
Update: 30th May 2007 : The Release date has been set at December 11th 2007 by Amazon.
The newest (May 21st) issue of Video Business trade magazine has an ad with a small sneak preview of the art for several upcoming TV-DVD sets from ABC and Disney/Buena Vista Home Entertainment. One of the box sets shown is Lost - The Complete 3rd Season: The Unexplored Experience, the art of which you can see to the left. Can't read that small print, and wondering how we could? We couldn't! The exact title comes from a trailer currently showing at Disney's new TVonDVDHits.com website (and don't think that we didn't notice it sounds a little bit like our own URL...so don't get confused, okay?). So, when will this release hit the store shelves? The street date hasn't been revealed yet, but expect it to come out timed to help promote the next new season of the show. Disney/Buena Vista is planning to announce each of these on May 31st, so stay tuned for more developments! Our thanks to readers like longtime friend Scott Lovelace, who helped us spot the art in the ad, and like Nick Sebek, who tipped us off about the trailer.
Source: TVonDVD