I was at work in the UK, I got a phone call (from my Mum as it happens) saying that the WTC had been hit according to the BBC newsflash she'd just seen.  I guess the fact that the BBC broke into an exisiting programme made it stand out, I think she'd only called me at work maybe once or twice before.

I hit the net, as one does and already the BBC, MSNBC, ABCNews, CNN (I'm sure I tried a bunch more sites) were crawling along; little more than leaking the occasional packet - at that time myself and the rest of the IT department were the first to know, so the company net feed was still ok.

Flash forward a few minutes, and the rest of the company knew.  Back then they only had a 2mb line, and it was borked with everyone hitting the web.  It only lasted for a few minutes, I was just about to make some changes to our firewall to drop the web traffic when it evaporated.  I was surprised by this until I wandered around the building to find everyone clustered around a couple of TV's watching the events unfold. 

As it happened the company was also sold on that day, but as you can imagine none of us really paid any attention to that news.