The only Guitar Hero and Rock Band playing I do is with my Girl Friend's Brother.  He has the XBOX 360 version of most of the games and also has 2 Guitars, which I believe only work on the 360.  One of them is wired (the one I use) and the other one he has is wireless. 

Anyway, I am going to buy Smash Hits and my own Guitar.

My question is... is there a Guitar Peripheral out there that does the following?

• Works on both Guitar Hero and Rock Band (hopefully also when the Beatles one coming-out).
• Works on both XBOX 306 and the PS3.
• Is Wireless.
• Has all the features, like slider, high-neck-solo keys, etc.

There is no such thing as a guitar working on both systems.

There is no guitar out that works on both the PS3 and Xbox 360. There is also no guitar that has both the slider and the solo-buttons.

My suggestion is just decide what console you want to buy Guitar Hero/Rock Band games on, and buy everything for that system (360 sounds like a good choice for you, that way you can share your guitars with your friend). I suggest buying a Guitar Hero: World Tour guitar or a Rock Band 2 guitar, since they seem to be the most efficient models out right now.

There isn't a guitar that has the slider bar and the solo buttons.

Unfortunately, you are out of luck with a guitar that works for both systems. Here is a chart that shows compatibility between games. Anything that works for Guitar Hero: World Tour should work on Smash Hits, Metallica, Van Halen, etc. Anything with Rock Band 2 should work with The Beatles, Lego, etc.

Thanks a lot guys!  It's a shame that the "ultimate" Guitar isn't out there.  I guess there would be licensing issues though, if it could work on both PS3 and XBOX 360.

Even with like the Street Fighter IV FightSticks, you can just buy the PS3 version, then use a (unlicensed) PS3-to-X360 converter with it, and it'll work perfectly with PS3, XBOX 360, and PC. 

Guitars are a whole different ball game though, as they aren't really controllers I guess (but the Wii ones function like this, I believe). 

Anyway, I guess I will be getting a XBOX 360 Guitar and start buying the games for the 360.  I will most likely get the GH: World Tour one and pray that it works with RB: Beatles.  Again, thank you for the input!

The new beatles signature guitars work on both systems and have the solo buttons

Hey guys, I ended-up buying the World Tour Guitar for the X360.  It works great and seems to be the most compatible at this time. 

Thank you so much for all the help, everyone!