I don't see why people are waiting on this software update. If the update does what they've said it'll do, that'll mean my full 3G area (since my Nokia 6280 several years ago) will come down to a 2-3 bar area. Brilliant.
If you think it's going to fix the left corner signal loss issue - read up on the subject more. It's caused by a fundamental design flaw (i.e. a hardware issue); (1) either it doesn't effect you due to the way you naturally hold your phone, (2) or it does. To give some suggested solutions to both of those scenarios respectively; (1) use your phone and get out of solution threads across the net, (2) or buy a bumper/eBay it for profit and get a 3GS.
As Apple currently stand, I wouldn't put it past them to hold the update till little over 30 days after the original i4 release date; preventing a good chunk of returns.