There were some early server issues on Apple's end with the launch of iOS 5 last Wednesday, but I bet that didn't deter too many from updating. According to Loyalytics,iOS 5 is already running on over 30% of all iOS devices being supported and has been available for only 6 days.
The iPad 2 and iPhone 4 have the highest adoption rates, but surprisingly, many of the older models have also updated to iOS 5. There are certainly a few jailbreakers that are either waiting for an untethered version of an iOS 5 jailbreak or iPad 2 owners waiting for any jailbreak of iOS 5 (along with iPhone 4S).
Hopefully an iOS 5 jailbreak, along with Siri on the iPad 2 will be coming soon as well!