There are far too many photos for me to repost, but here is a link to a gallery on TomsGuide.com
There are some very interesting costumes and some impressive work, check it out.
BlizzCon 2011 Cosplay Gallery
Here are a few favorites of mine though:
Who knew BlizzCon had pony rides?
Death Knight? Or Paladin? No clue…
Non-Artificial Light! Ow!