The above image is a glance at the traffic that Cydia underwent in the course of roughly a day. Quite impressive, and obviously enough to cripple most server systems. What is even more impressive is that it seems as if this may just be the new norm for the system, as so many new people jailbroke using Evasi0n.
There is good news: despite Cydia being almost unresponsive for most of the day yesterday, it appears that the worst is over. Saurik has put up a notice in Cydia itself, which basically states that all of Cydia and its subsystems are back online (including the payment system!), albeit potentially slow in some cases. That should really go without saying, though – take a look at that traffic!
Still, report back in the forums on your own experiences with Cydia!