Microsoft launches a new assault on Google search with Live Search cashback today.

Microsoft hands you hard cash, if you buy a product through Live Search. Depending on the product Live Search cashback gives you 2% to 30% cash back.
To accumulate cashback you need to register an account of course.
The official announcement is later today, but the Live Search cashback site is already online.
I tested for instance the offers on the iPod touch 16GB and got the lowest final price after cashback of $330.52. The Apple store sells this iPod for $399 and Amazon still wants $369 for it.
The Garmin nuvi for instance is offered after cashback at $311.52. Amazon.com charges $342.99.

Live Search cashback looks pretty promising after my first tests of the prices. I do not think it will be causing big harm to Google, but I see much more danger for price comparison sites. Live Search cashback can offer better deals on the same shop offers through the extra cashback rebate.
Try Live Search cashback here. More details on the Seattle PI.