Update:

>>> does the A2 have AltiVec/VMX?

>> Don't know but they could always add it.

> Yes, of course they could, but what I would like to know is
> whether IBM's stock A2 core (as used in the PowerEN and
> Power BQC chips) has it. I ask because I've read conflicting
> third party statements on that matter (and no statement by IBM itself).

http://www.theregister.co.uk/2011/08/22/ibm_bluegene_q_chip/

As that detailed article doesn't mention AltiVec/VMX for the A2 core I assume that it's not there.