The official website of the BLOOD-C TV Anime series released a PV for Episode 1! Check it out at http://www.blood-c.jp/.
The TV Series launching date has also been revealed, broadcast will start on July 7.
Update: The video was strangely removed from the website (although CLAMP’s Ohkawa herself made a comment about it on CLAMP-NET.COM). You can still watch the PV via YouTube: http://www.youtube.com/watch?v=-wBTvv5MjwM