I just recently returned from Austria where this was common practice in nightclubs. Generally the camera did not matter. I saw D40s, D50s, D100s, D2Xes just like I saw Canon 350Ds all the way up to 5Ds, heck a few people were shooting with little point and shoot cams.
The thing they all had in common was big flashes. Pretty much all Nikon flashes I saw were top of the line SB-800s, the canon's looked equally expensive.
A lot of people were also using very fast lenses. Even the D40 I saw had a 17-55mm f2.8 lens on it and many of the photographers from the looks of their pictures were using this fast aperature, bumping up the ISO to 400-800 and slow-syncing.
The other thing they had in common was I didn't see a single direct flash. The SB-800s were usually used with diffusers bounced off the ceiling, and those with flash cards used their flashcards and still bounced off the ceiling. Those without, made some. Some guy had a small tupperware container on his flash litterally held on by tape, and another used a few rubber bands and some white ID cards or business cards as a flash card, again indirectly bouncing from the ceiling.
Good luck.