I don't know if the Szczerbiak/Garnett problems were racially motivated or not, but it's no secret that the two never got along. The reason, to me, seems irrelevant.
IMHO, the Celtics won this trade. Szczerbiak's a great fit with Paul Pierce, with his outside shooting, and the fact that he's big enough to move to the 3 and give Pierce the chance to move back to the 2, where he's more comfortable. Losing Blount and the big contract he has, is nice, too, though the long term cap ramifications are pretty much evened out by Szczerbiak's deal...though at least Wally earns most of his salary.
The T-Wolves...eh, I'm not sure what their angle is apart from their constant desire to move Wally since he and KG hate each other. They probably got the best player back that they could, though I would have liked to see them swap Szczerbiak for Artest. I think KG would have put Artest in line.