from my understanding, hard drive recorders using HD will record in the AVCHD format which will ALWAYS require conversion by iMovie into AIC (Apple Intermediate Codec)... and then you can edit from there...
of course, this conversion happens behind the scenes.. you just hook your camcorder up .. fire up imovie, which will recognise it.. select what clips you want and usually it will import on a 1:1 basis (ie, for every 1 minute of footage, it will take 1 min to transfer to mac) - could depend on your mac of course..
as for which HDD camcorders? sony sr12 is a decent runner.. but you could also search around the forums as this type of stuff always crops up