Is anyone else finding that Gmail is receiving messages up to 3 or more hours after they were originally sent? This started affecting my account yesterday afternoon, and it has not yet resolved itself.

Yes, I'm finding the same

Weird. This morning I saw two obvious spam messages in my inbox: the worst spam filter would've detected them.

I wonder why I still get spam into my spam box... I enabled the filter you talked about before Ionut, which should automatically move spam mail to the trash, but I still always have a couple of spam mails in my spam box.

Update: not all messages are three hours late. But I'm not used to the half-hour delay I'm getting with some.

(my own message above):
I think all the messages were from gmail.com addresses. This could be the explanation:
http://diggreponsitory.blogspot.com/2007/12/spammers-penetrate-gmail-spam-filters.html

All I could say is that the number of new messages in my spam box used to sit at around 2000 and now it's at about 500 – and I rarely get spam in my inbox