I was among the reviewers this year and really curious about who would win. My votes were a bit different from the final result, but then it was tricky to compare the 2007 submissions which all seemed to have their strengths in different aspects of the Challenge criteria (e.g. Revyu scores high with regard to "Ease of Use", Potluck just blows you away, CHIP is super smart, GroupMe is both visionary and fun, iFanzy/SenSee is already marketable, etc.). So, congratulations to all of them:
1st Prize: Revyu.com
2nd Prize: Potluck
3rd Prize: CHIP Demonstrator
Runner-ups: GroupMe and iFanzy.
From the overall submissions, I found GroupMe, mle, and SemClip very interesting. They have a focus on instant utility and are close to the practical RDF stuff I'm interested in myself.
Looking forward to next year.
Oh, and someone should give an award to Jen Golbeck, Peter Mika and the other challenge organizers as well!