Ok this is the only real issue i have had with Lion GM and it never happened in SL. My modem is still working and my PS3 and Xbox still connect to the net but on my Mac the net will cut out randomly and comes back on after a few minutes??? Anyone else had this issue?
This has actually been reported here as an issue with SL for a long time. I have this problem with that OS.
But I don't use the Lion GM long enough to see if it's been fixed. I guess not.

My only solution under SL is to toggle Airport off for a few seconds then toggle it back on.
It's happened to me quite a few times over the past few days. My iPhone will still be connected and working fine, but my Macbook requires me to toggle the Airport to resume connectivity. bummer. I should add, I did not have this issue with Snow Leopard.
Wow, I'm not thrilled to read this. I have not tried out Lion yet. I do have that intermittent WiFi connection issue wtih my 13"MBP and Snow Leopard (not with anything else - iPhone, iPad, iPod -- all with current software-- and no problem with the MBA running Leopard either). Sometimes I can get it back by just clicking on the Airport icon in menu or opening a new tab with some bookmarked quick-loading thing like the regional weather summary. But sometimes have to on-off Airport, once in a great while I have to restart the machine to get a connection (usually power cycle the router as well if that happens, just to have a fresh go).
I have read lots of threads about this problem (relating to Snow Leopard, I hasten to say) to the point where experimental fixes all feel like a bunch of superstitious rituals no matter what I do. I was kinda hoping that once I got Lion on board, the MBP would snap out of it. That's the only reason I have not taken it up with the Apple tech again, since my machine is refurb purchased in March -- all they did was have me reset the SMC which had no visible impact on how often this dropout happens with Snow Leopard.
I figured that I'd do a clean install of SL, get the Lion from app store and upgrade, then hammer on the WiFi before adding back any third party stuff (of which I have nothing exotic anyway). Now I'm feeling like Lion is not going to help me out but I'll still take my planned upgrade approach and see how it goes.
The router's a DSL-modem-router Siemens Gigaset SE567... no problems with ANY device except with the MBP13" running SL. Having a slow DSL connection in prime-time and sometimes on weekends does not, of course, help me troubleshoot this thing. I've also even wondered about Firefox 4, and now Firefox 5. So I've gone with Safari sometimes but the problem turns up again.
(Tears hair out, apologizes for rant and slightly off-topic since for me it's still an SL issue, but one that I was hoping Lion would resolve... hope info helps someone sometime --> maybe I'm looking at you apple, but maybe I'm looking at the router firmware?).