See below for the current ranking of the contest.
Cuocthiseo dot com is on the top recently, two banned blogs at My Opera follow, then few images capturing Google search for cuocthiseo at Flickr, and on 5th place is cuocthiseo dot blogspot dot com. (You can see that Google is not so smart by this search :) ).
Some contestants complained that by cuocthiseo dot com joining, contest becomes unfair for others, because Google gives too much ranking value to keywords-match domain.
Personally, I think choosing domain name is an important part of SEO. So, why not fair? The owner of cuocthiseo dot com already made a step ahead, because he is good SEOer :) .
I joined about two weeks late and chosen free blog at blogger for the contest. By this way, I can see many disadvantages, but victory should be more amazing by this way :D .
As my experiences, blogs at Wordpress seem to be better in SEO than blogs at Blogger. However, my Internet connection is very slow when accessing Wordpress blogs. So, there is one more disadvantage :( .
Anyway, that's a contest and I enjoy contesting :) .