Sorry to Aero and co. Pretty bleak times in the City. Spoken to a few friends in a couple of the institutions where I used to work and even those unscathed by this are in shock - not just trading, but across capital markets, corporate finance and asset management. Lehman's always been held in pretty high regard and I've always found the people there to be smart and straight.
Apparently as far as Lehmans going down affects the other banks, there's going to be minimal direct effect. Most of its major counterparties were net or long on a trading basis (which partly explains the situation) so none of them are owed significant amounts of money by Lehmans. That's part of the reason the Fed let them fail - it wouldn't drag down anyone else. Much more scarily, I understand that not only Merrill's heading the same way very quickly and that if they had gone down, they'd have pulled down Morgan Stanley due to the massively exposed nature of the trading positions between them. That's why the deal between Merrill's and BoA was agreed and approved so quickly. Will be interesting to see what Goldman and Morgan Stanley report in their Q3 results.
On the plus side, if you care to see it, I really struggle to see this sort of collapse happening to the major retail banks (i.e. HSBC, Citi, JPM, Barclays, HBOS etc.) for two reasons. Firstly, what brought down Northern Rock, Bear Stearns and Lehmans was not their 'toxic' securities per se, but the fact that other institutions stopped lending to them because they were scared about the nature/ value/ amount of these securities coupled with the mis-matched nature of their funding and liabilities. As a result they were unable to meet the short term obligations which they did have. The retail banks have their own pool of liquidity to draw upon (i.e. deposit accounts etc). Secondly, the governments won't let a major retail bank fail as the fall-out would be catastrophic - they stepped in for NR, Fannie Mae and Freddic Mac and they'd do so again.
Oh, and as far as "hedge funds" go, they're neither good nor bad to my mind, however, they do typically create much more market volatility which in this environment is not a great thing.