"How Come.?" regarding Google API

non commercial but yet used for commercial purpose

[esengulov]

I am developing a web based public application that will have one of the tools displaying domain rankings on Google, Yahoo and MSN for user provided keywords. Eventhough mostly free some aspect of the application are commercial.

I red on Google that their API can not be utilised for commercial purpose yet I am aware of some commercial applications that do use it in the for same purposes outlined above.(ex; sitsell's-Site BuildIt Tool). Am I missing something here?

All replies will be much appreciated