bradstewart: Great program... my ping went from an average of 350ms to well over 1000ms. I've tried it several times in the past but never with any decent result.
last but not least, it allows you to turn off nagles (I think thats what it's called) algorithm which basically wont allow you to send packets under a certain size, and will wait till you have generated enough data before it sends it off to blizzard. This can cause lag while your computer waits for enough data to be generated.
If the server gets overloaded (it can take a lot, but smoothping is not the first one to offer this service and all the others before have suffered from overloading) then you basically end up back at square one.