Hypersmurf said:So, the Sage says they don't stack, which is a point in favour of "They don't stack".
The lead designer for 3.5 says they don't stack, which is a big point in favour of "They don't stack".
And Customer Service says they do stack, which is the biggest point in favour of "They don't stack"...
-Hyp.
Ok, customer support agrees with me, I must be wrong.

Seriously though, the rules don't state this anywhere. I expect it in the FAQ or errata, but untill then, this is all unofficial and we only have the rules. There is no reason in the rules they can't stack. I don't intend to build a character on this if it is most likely going to be changed, however.