Google is promoting Google Music by paying Bing some big money for search result ads. I know Bing still advertises on Google results. You can see when searching Google for "Bing". Now when you search Bing for music, like "Journey Songs", you get Google Music ads. It seems like a waste of money for Google, when they have pleanty of their own advertising resources at their exposure...not to mention Google search itself.
It's never a waste of money to advertise your services on a competitors site...it's very clever. Keep in mind they may adress potential customers or new user they'd never reach via their own network.
The percentage could be small, but Bing got a significant number of users. Its a good idea trying to tap into an audience using a competitor site
well i think its still one of their marketing strategy.. i don't see anything wrong with that.. and i'm sure that they are not gonna do it if its not going to work..