China: Tibetan protesters raise flag outside Olympic stadium · Global Voices
John Kennedy

Still waiting (updating below) for more details, but Qik.com vlogger Noel Hidalgo is at the scene and giving updates via Twitter. Here's a video he took just a few minutes ago not far from the Olympic bird's nest:
Noel has just finished uploading a second video, in which he reports that Chinese firemen have taken down one protester and one appears to be coming down the other pole; no sign of the third protester who was stationed on the ground as seen in the clip above:
Tweet timeline (Beijing time):
6:38am @noneck:
Shoeed west away from tibetan protesters climbing polls outside of nest
6:42am @noneck:
There is now a tibetan protester climbing a western poll. Moving to att pim for qik
7:14am @noneck:
Wow! The locals are hot and bothered. Heading back to the hotel.
7:28am @noneck:
Now i'm being followed by a little old lady who told the last cab driver to kick me out. On foot looking for other followers.
7:33 @noneck:
Found a cab and now i'm heading for some coffee to chill for a bit.