I think the gateway for session.minecraft.net (the thing that logs you into servers) is down. It would explain the 502 error and the fact that we can log in but not do this. EDIT: I can log in just fine, but it gives me a 502 error upon server connection. Tested on a few random servers as well as my private one.
To Everyone Who Can't Join Ok, I said this on irc but I'll say it here too (because I can). The error here is a 502 error regarding session.minecraft.net. Dumbed down 100 times, this is what's happening: Normally to access anything on the internet you go through a door (the gateway, in this case session.minecraft.net) Normally the door is open, but right now it's locked and they can't find the key. Updating to the latest snapshot won't do anything, because its like changing the clothes you're wearing and that won't open the door. All you can do now is wait for Mojang to find the key and open the door. ...and if that was too dumbed down for you, a technical explanation at http://www.checkupdown.com/status/E502.html
