Gmail down?

From about 11.30 today on Google's Gmail service is down showing an error "502 - Bad Gateway" as shown below.

Gmail - 502 Bad Gateway

Possible that a giant like Google (which has all my respect) let down for almost 2 hours for a service like Gmail that level of usage is immediately after the search engine?

Another human error ?

UPDATE # 1: After 2 hours down to 13.30 is back up and running the Gmail service.

UPDATE # 2: Currently there are no official explanations. On the support page of Gmail is the following warning:

We're aware of a problem with Gmail Affecting a number of users. This problem occurred at Approximately 1.30am Pacific Time. We're working hard to resolve this problem and will post updates as we have them. We apologize for any inconvenience this has That Caused.

UPDATE # 3: [24/2/2009 - 15.02] - Further update of the Notice to users:

Many of our users HAD entry has difficulty Gmail today. The problem is now resolved and users have access HAD restored. We know how important Gmail is to our users, so we take issues like this very Seriously, and we apologize for the inconvenience.