From the
Wall St Journal:
Microsoft Corp. hopes to make gains on Google Inc. in the lucrative business of Internet search through a new service that pays consumers who buy items they find through the software company's search service.
They must've been reading Broadstuff

- we
noted last year, re matching YouTube, that organic growth via customer motivation was a real option:
Broadstuff Biz Case (expurgated version*)
Cost of Service build - $1m
Cost of Operation before breakeven - $100m
Cost of "persuading" critical mass of YouTube UGC videos onto new service = $5 / video x 50 million clips = $ 250m (added to their content)
No reason one can't apply it to search......for a while anyway.