You like dragons?
Hmm... the expansion in signature space... Well, at least I finally can have my signature uncropped!
600x350 seems to be quite a large amount of space to fool around with, when you consider what should be in a signature. But in the end, it works out, huh?
Having the scroll bars appear when the signature is oversized should also make things easier for staff and users alike.
Also, one hypothetical situation - let's say that there's a 1MB image in use in the signature. There are multiple instances of the same image (exact same URL) in the same signature. All images combined fit within the signature size. What'll that be?