There was a six minute outage of all of WordPress.com about an hour ago, starting at approximately 16:19 EDT till 16:25 EDT today, Sept 6th, 2011.
With the front end caching some visitors would not have experienced it.
It appears to have been a programming error introduced into our lower level MySQL database interaction code, which explains why the symptom was a blank page.
status.automattic.com now shows:
At 4:19 EDT this afternoon, one of our developers accidentally deployed some code to WordPress.com that caused pages to stop loading and instead return a 500 error. This changed was reverted at 4:25 and everything returned to normal. Sorry for the inconvenience!
Technical operations is investigating with the specific programming group to see where our processes and measures broke down.