There’s a lot of buzz in the blogosphere about the upcoming Google Nexus One smartphone. While nothing is to be sure yet, rumors have it that the phone will appear on T-Mobile sometime soon, and that the phone may have more to do with advertising than competing Android models. The FTC approved the Nexus One about 15 hours ago, so we can at least be sure it’s not all rumor at this point.

But why is Google getting into the mobile hardware space? Google is, at heart, a mobile advertising company. Why would they care to get into the hardware business, unless they are looking for a way to disrupt the mobile industry?

Lots of bloggers are speculating that Google is looking to offer an affordable SIM-free handset by supporting it with advertising. Google’s $750M acquisition of AdMob surely could be related to their plan to get into mobile hardware.

The idea of an ad-supported phone is exciting from a mobile marketing perspective. Getting your audience to opt-in to mobile campaigns is a challenge, but if a user is willing to be targeted with relevant marketing messaging in order to have the latest cool phone at an affordable price, you’ll get your audience.

Of course, how much marketing an advertising can one mobile phone support? Would any of this really be enough to offset the costs of having an SIM-free handset? These questions are all still based on conjecture, but it wouldn’t be too surprising to see Google creatively using advertising to support its Nexus One phone and other G-phone offerings in the future.

What do you think of all the rumors? Would marketing to automatically opted-in Nexus One customers be useful to you?