As far as cels went I didn't see much new either.  
With the show being so huge though, there was
always something to do.  The past few years at 
sdcc it's seemed that there have been some great
guests that just show up as guests of companies,
and subsuquently don't show up the guest list.
The hard part is tracking them down or looking
at each booth to see if they have some special
signing like it was with the case of Katsura.
I was lucky enough to get this from him, he
was a really nice man and was very cool to watch
him draw with such skill so effortlessly.