Rather than an "Evite killer," think of it more as a home page or website for events, with public events eventually to most likely be integrated into the broader local database and other services that Microsoft has. Currently it integrates pretty seamlessly into Windows Live Spaces, as well as third party calendars (e.g., iCal, Yahoo, Google). There are a range of "social networking" elements built into the application and it's fairly customizable. One of the interesting features or differentiators here is the idea that after the event is done it becomes a "scrapbook" or photosharing site and so lives on beyond the event itself.