Am I the only one getting a stream of NetDB errors (with the occasional HTTP 500 or 502)? I guess I'll just have to wait until... whatever server it's trying to connect to is up and running. I haven't had a chance to install a single package yet.
Edit: Popping over to r/jailbreak confirms it, I guess it'll be a while before things calm down. I just hope I can get f.lux before I have to go to work.
Confirming this as well... If you see this error, NetDB, Failed to fetch, etc., it is not any problem with your iDevice, Cydia, the jailbreak, or really anything at all. In fact, if you are seeing this right now on 2/4/2013, it most likely means everything is working properly!
The servers that provide the apps, the 'sources', are overloaded with people trying to download. Waiting until the servers are less loaded is the only solution, right now.