Just loged in, and found Facebook is down for past half an hour atleast for me. After searching net, it looks like Facebook is currently having major issues with their site, with some users reporting the service is not accessible at all, and others saying that pages are only partially loading for them. Which means the issue is likely isolated to a specific datacenter or set of datacenters.
It appears those who are able to gain access are seeing other issues such as not being able to "like" posts and the ability to update their status not working.
Twitter is also being flooded with messages from users complaining of the errors.
Down Right Now reports that the site went down a few hours ago for some, with around 5,000 unique reports from Twitter indicating issues.
Facebook updated their official page saying: