Microsoft is developing a brand ambassador network on college campuses nationwide to provide grassroots support for Microsoft’s i’m initiative.

Every time a person starts a conversation using i’m (for instant messaging), Microsoft shares a portion of the program’s advertising revenue with organizations dedicated to social causes.

Ads for i’m are popping up all over the Internet. In addition, generate buzz across a targeted 35 campuses, 70 brand ambassadors will tap into the students, groups and resources that best impact their own campuses. Ambassadors will be provided marketing budgets and materials and tasked with developing plans specific to their campuses, which could entail hosting large-scale events, tying into local causes and organizations or generating local press. In addition, ambassadors will spread the word to their peers through all forms of personal interactions such as traditional word-of-mouth, personal blogs and their on and offline social networks.

Microsoft is using RepNation to organize and run the WOM campaign.