we are making an app which
need to support iPod Touch 2G
and more than iPhone 3GS
.
Is that possible?
EDIT: I don't want to support 3G
.
The 3GS is not difficult to support; it's an armv7 processor, and can be targeted with Xcode 4.5. They'll run iOS 5 or even iOS 6. Aside from having more limited memory, they're not difficult to develop for at all.
The 2nd Generation iPod Touch (and the third generation, for that matter) are both equipped with an armv6 family processor.
The 3GS is a pretty reasonable requirement, but you should not target the older iPod touch models.