Grand Theft Auto 3 won't make its debut as a PS2 Classic download today. The PS2 Classic will instead arrive on some future date, and the PlayStation Blog says it'll update us when as soon as possible.
As for things that do exist today, The Expendables 2 is a thing you can pay money to download, and is joined by PS2 Classic War of the Monsters and the aforementioned Transformers: War for Cybertron demo – you don't have to pay money for that last thing. Pre-orders for next week's release, Sound Shapes, are also open – it's 20% off for PS Plus members and all pre-orderers will receive a free PS3 theme. We haven't seen the theme, but it probably has some shapes in it, probably not much in the way of sound.
Update: According to a comment on the PlayStation Blog from Morgan Haro, community manager for digital platforms at PlayStation, the reason GTA 3 isn't available for download this week is due to a licensing issue involving the soundtrack. "There were some last minute issues with getting clearance for a certain audio track in the game; but the teams at Rockstar are on it to review how to best get this title on PSN."