JTF
As a long time sufferer of wifi dropouts on my 2008 Intel iMac, I have been trawling these forums from time to time and am now taking a greater interest as the dropouts have increased since I upgraded to Lion. I see the practical point you are making by suggesting that people use the workarounds for the time being, but you must agree that the whole issue makes Apple look like a bit of a joke!
Anyway, in the spirit of self-help which you are promoting, I started the ping in terminal last night and for a couple of hours it kept pinging without any timeouts and I could browse the web from time to time without issue. I left my computer running overnight, and when I looked at it this morning, the ping had all of a sudden timed out during the night and never started working again - no web browsing possible. I rebooted (but did not run the ping again) and web browsing worked again for a few minutes (several tabs open), then I went to make a coffee and came back and the wifi had died again.
I have tried the channel changes, the wake from sleep setting, the WPA2, WEP, IPv6 changes and nothing fixes the problem for good.
I do agree that doing a continuous ping or something else (i.e. using a citrix terminal connection to my work server, or watching a movie stored on my imac through my AppleTV) which keeps a constant stream of data packets going back and forth over the wifi connection does keep the wifi connection open for longer, but, in my case at least, it is not even a temporary fix, as eventually the wifi drops out (the citrix terminal will stop responding, and the movie will stop playing over the AppleTV). I have seen this happen repeatedly with my iMac over the last few years and it has now got worse with Lion.
I guess it must be an issue with the wifi card driver, and I cannot understand why it is taking Apple so **** long to fix it or even acknowledge it is a problem!!