Well it was a bit of a surprise because Lehman are such a big, old bank. Its was very profitable (until this year) too, so I am still surprised why no one rescued it. I guess most banks are worried about themselves now so didn't even consider it. We did the most trades on the LSE and TSE - iirc ~15% of the LSE volume... so it has hit the LSE quite bad... the stock had been heading downwards for a while, people were upset about that. People were quiet on the trading floor last week, wasn't as loud and lively as it usually is because everyone was worried about their job, their bonus and the share value.
It will make a bad short term difference, we were too connected. The investors will lose confidence in the banks and the markets.
AIG might go bankrupt next, but the fed will probably help them out more because they are an insurance company...
EDIT: this is a good article for anyone interested