I use one of ide hdd case bought from www.compgeek.com and it can hotswap. I am using it both on linux and netbsd. If you're interested, stop by 2249 anytime you want.
For scsi, there're similar hdd case you can use. SCA is developped for this purpose iirc. But I tried regular hdd (50pin and 68pin) with adaptech 2940 (or somthing like that, it was ajay's), and it worked fine (the scsi ctrler did not support the hotswap. I just tried). t
