What can a search engine possibly compute anything other than the ridiculous 2^2^2^2...?
Who would type that question to a search engine anyway? No, no, Microsoft is confused, you use Mathematica 7.0 for that kind of computation.
The best today's idiotic search engines could possibly hope to do is to add/subtract some numbers, provide unit/currency conversions and that's all. Google is already doing all that.
Unless Bing servers are some clever cousins of HAL, adding some funky math skills to them won't do a bit of a difference. It's a loooong shot before the search engine actually gathers unrelated information and connects it to the actual query, doing some useful computation in between.
Sorry Microsoft, this doesn't fly.