Snow Leopard updated
 

I installed the new update of SL, after which I did a SuperDuper backup.
Sorry to report that, whatever Apple did to the system, it had no effect on the speed of SD's backup.
Took a couple of minutes longer, but I guess it's because of the new files, which also including an updated iTunes as well.

In fairness
 

When I did the backup, the volume being copied TO did not have the updated SL installed. Of course, it does now. I have no idea if it made any difference, but thought it should be disclosed.

I wouldn't expect their update to improve this; as indicated in the blog, we're working on it (in fact, the fix is in broad testing now).