Yes, but at this moment in time no.
Nor is there is an untether for any iDevice on 5.0 (or 5.0.1)
It's not a case of testing it, he has to actually make it work first lol by running different code etc... the exploit used in 4.3.3 and 5.0 was closed in 5.0.1 so they need to find a new way of implimenting and executing the code, then test it for bugs like crashing/reboots etc...
I'd expect an untether to be released before Christmas, but maybe not for 5.0.1.
The iPhone Devs released a previous jailbreak around Christmas time last year and they typically release jailbreaks on sundays, which they call fun-days