There was some uncertainty as to whether or not the Pistons would keep Walker Russell, especially with Will Bynum and Ben Gordon returning soon, but it appears the team will in fact hang on to him and guarantee his contract, according to HoopsHype:
The contract becomes officially guaranteed on February 10. HoopsHype followed the above tweet up with a nice little nugget that I did not realize before: Russell is the first call up ever by the Pistons.