Yes, if you login and your cookie is sniffed and spoofed then basically you just allowed the attacker to login as you at the same time.
Minimizing it is a little bit different: you can use a secure proxy/tunnel, you can limit your unencrypted wireless activity, you can make sure that sites that should be SSL encrypted are (stripping SSL is common when password sniffing) and you can avoid these services while on open wifi networks.
So remember to logout.
VPN is really the best overall option.
On reporting it, the response was essentially, "oh you didn't have to go to that much trouble, you could have just used your user/pass from curl…" Completely obvious to the fact that they're app/site was completely vulnerable to session hijacking.
One of the problems of app frameworks, if you don't know what they're doing (and more importantly, not doing) you can get yourself in a heap of trouble before you even realize there's an issue. But boy, you sure can make it to market fast. shakes head
Logging out doesn't kill the session.
It will, however, stop unauthorised computers from sniffing any network data.
Are you sure that neither WEP nor WPA/WPA2 do it this way?
Are you suggesting that no generation of WEP or WPA protects against other authorized wireless users of the same AP, because they're "on your network"?
[rewritten completely to seek clarification]
If you have control over the internet between the AP and your server, then you're safe. If you don't, then how safe you are depends on how much you can trust the owner of each router along the way. In general, you should be okay, except that every now and then you might end up on an untrusted router, and it's then game over.
This exploit is for insecure Wifi networks- so only using encrypted Wi-fi or Ethernet would seem to remove this attack vector. Is there a real risk that someone (besides the government) can see your cookie?