I’m not sure if the PS3 firmware updates (currently at 1.54, again) are responsible for this, or if Comcast did something to their network, but I have found that it is now a lot easier to connect. You no longer have to power cycle your cable modem when you swap back and forth between your PC and your PS3. This makes things a hell of a lot easier.
However, that still doesn’t help much you if you buy a Playstation that has the old firmware and you need to connect to update (classic Catch-22, although you can always download the firmware update to a memory stick and import it to the PS3 in that manner). So, if you’ve just bought a PS3 with the old firmware, you’ll still need some help, and I’d like to once again refer you to how I managed to fix the 80710102 problem.