The main reason they are pushing new terms appears to be for OAuth, which is a authentication standard allowing for cross domain credentialing. OAuth is what let's you login to sites with things like Facebook, for example.
This probably gives them more robust data collection and reporting. It also lets them cross reference user data with other repositories, likely for advertising purposes.
As a developer, I find it slightly disconcerting, but it's also pretty much where the web is going. OAuth is totally widespread and I have implemented it plenty of times where I work. It's not nefarious at all.
It's a bit concerning because I don't want Rivals to be associated with my social networks or want that data correlated. I'd rather be able to speak my mind on Rivals with out freaks knowing where I live. Rivals itself already knows where I live, but I don't want that exposed to the public. If it's for analytics / reporting internally and Yahoo protects the data I don't have a problem with it.
