I'm sure you can if the sata port supports hot-swapping. You can configure this in the bios if your mobo supports it.
Surely it's the same as the hot-swappable drive bays some cases have (650d)
SATA's hot swap, so go nuts.
The only issue you might hit is if the mobo / RAID controller doesn't support hot swap, in which case you'll have to reboot for the new disk to be detected.
^That's different (and reckless)