Relics and Rituals 2 DOES have some psi stuff in it. Some of it is a repeat as SS adopts ITCK's Psion varient class as their own for offical SL games.
Some of it is new, such as optional fatigue rules to help balance out the fact that few SL challenges have defense against psionics. The other stuff is fluff which introduces the idea of an extinct race that used to use psionics and has left a few ruins and psionic artifact around, including a virus that give psionic powers and dowloads the ancient race's own language into the victim.
To recap ITCK's highlights:
* "Converts" PHB spells into psionic powers. IMO, this was the most coolest and disppointing part. It is great that now psions have a large library of powers, the bad part was that Bruce basicly did a search and replace on psionic manifstations for spell componets and assigned disiplines to the spells. The levels stayed the same.
*The print edition has not only the varient psion, but also the varient PrCs of the PsiHB. The biggest and best change? "+1 manifester level" instead of restarting the displine chart again.
*Trading PP for Scaling damage. Very cool if you don't have Chain Link in your game.
*The Colorless Adpet class, gesalt baby!