Movie Player reports that James Marsters is currently involved with the sequel to Dragonball Evolution entitled, Dragonball 2 : Reborn. Here is a translated quote from that website.

James recently participated in the series “Lie To Me and The Super Hero Squad and is involved in the sequel Dragonball 2: Reborn, where he plays the role of Piccolo.

Note that it is only a rumor that should be taken with a grain of salt. They might just be re-reporting exactly what IMDB has already informed us (and as stated in the last post, IMDB is not very reliable). 20th Century FOX is keeping the whole sequel talk hush hush at the moment.