Leaders in Video DSLR work
I guess I can call them leaders. They have done all sorts of work with these Video DSLR cameras, ranging from digital film, to broadcast television.
Phillip Bloom - A DP, Cameraman, and a Filmmaker, he's done so many awesome projects my skin is turning a shade of green with envy. This link directly goes to his Video DSLR section of his site, but I encourage you to browse around and check him out. Very cool. Also, just for fun, check out the hilarious spoof of "Downfall" that Bloom made. Anyone who has owned these early cameras knows the hilarity of this spoof. (P.s., I guess this is my unofficial endorsement of Bloom, but he has created tutorial DVDs on how to use the 5DMkII and the 7D that, IMO, is imperative to anyone wanting to do serious work with these Video DSLRs. Get one.)
The Bui Brothers - They've done some great early work with the Canon 5DmkII and 7D. Their blog post using the 5DMkII for a broadcast commercial for JINX clothing is nice and they even edited the post when the new firmware came out. They're also master photographers and have done amazing work. They also have done a photoshoot with my college friend Justine Ezarik .
Vimeo - Okay, this isn't a person, but a group of very talented artist and are very worthy of recognition. I get tons of enjoyment just by watching these videos, and truthfully, I am inspired to do this level of great stuff. There are plenty of groups featuring content from these cameras, but I recommend the the 'ULTIMATE 5D MK2' group and the Canon EOS 7D as my pick of the best.
Oops! My "post" finger got ahead of me, as I neglected one last awesome Video DSLR guy.
Vincent Laforet - Known for being presumably the very FIRST person to do work with the HD Video function on the 5DMkII when it was still in pre-production. His video, "Reverie" was awesome. Canon soon came after him again to do an interview and get some insight on working with the camera.
Here's a link to the interview. Very insightful.
Shane Hurlbut's doing some neat stuff too - http://hurlbutvisuals.com/blog - how many people can say that they've mounted a Panavision Primo to their 5DMkii?