"AltiVec technology for the e6500 core is essentially the same as AltiVec technology from the e600 core, except for the following:
- Adds new instructions for computing absolute differences [...] These speed up in the inner loop of motion estimation video processing
- Adds new instructions for dealing with misaligned vectors more easily [...]
- Adds new instructions for dealing with elements of vectors [...] These allow loading/storing of arbitrary elements to arbitrary addresses
- Instructions for moving data from GPRn to vector register [...]"

Doesn't look like too much.
It is hard to tell how much of a performance increase this will provide, but then, it beats not having AltiVec at all.