If the port in question supports hot-plugging (a moderately complex question), and you are running Win7, you can. But hot-plugging with a cable is not a good idea; there is too much risk of touching the wrong thing while the system is running. Be very careful.
I hot-plug all the time, but I use hot-plug bays and do it with my case closed.
EDIT: Why would you hot-plug an SSD? I only do it for my backup drives, and an SSD would obviously be overkill for a backup drive. My OS is on my SSD, but I would not hot-swap my OS drive. Just curious.