From Bob Finnan, a News-Herald guy who covers the Cavs (I think):
Sources indicate Celtics director of basketball operations Danny Ainge will likely buy out forward Paul Pierce's $15 million contract for next year ($5 million is guaranteed). If that happens, Grant should be first in line to try to acquire Pierce's services. However, before anyone gets too giddy, Pierce will likely want to go to a serious contender.
I'd like to know what the sources are before giving merit to this, but it wouldn't surprise me with the Doc leaving rumors going on.