Some more tracks have been announced for the upcoming Guitar Hero Encore: Rocks the 80s:

Hold On Loosely (as made famous by .38 Special)
No One Like You (as made famous by Scorpions)
Only a Lad (as made famous by Oingo Boingo)
Radar Love (as made famous by White Lion)
Ballroom Blitz (as made famous by Krokus)
The Warrior (by Scandal)
What I Like About You (as made famous by The Romantics)
Wrath Child (as made famous by Iron Maiden)

More information is available in the press release. A bunch of new screenshots are also available.

Does anyone know a release date for this?

Yeah, I was wondering if there was any idea of an ETA for this?

Guitar Hero Encore: Rocks the 80s, published by RedOctane® and developed by Harmonix, will be available in August for the PlayStation®2 computer entertainment system.

Is it a standalone game, or do you somehow need the original guitar hero for it to work? Cos I heard its only like 30 songs, which is less than half what Guitar Hero 2 has, if they try and sell it for the same price as a full game I'm calling shenanigans.

it's standalone but I'm pretty sure you can use the GH1/GH2 controllers. I'm not positive but I think you have the option of buying with an 80s style guitar as well