Yesterday, the web version of Gmail and Google Apps went down for pretty much everyone. The downtime was about an hour plus for most people and the world stopped. Why did it happen? Basically, some routers got overloaded and shut down, which caused a rippled effect. For the full details, see Google's blog post with them being extremely clear about the technical issues (I love it when people do that).
I was honestly in disbelief to learn about many people do not have IMAP or POP access to their Gmail accounts. You can use the web interface 99% of the time, but as a backup, get an email client (be it desktop or mobile) and set up IMAP (preferably) to work with your Gmail account. Why? Well, in yesterday's case, IMAP and POP were working fine, but the web site was down. So those who had access to their Gmail account via IMAP and POP, were in luck.
Anyway, Twitter was going wild with "is gmail down" tweets. But the forums were going wild as well.