Does the shutter speed and focal length rule of thumb apply to cropped sensor cameras?

So, the rule of thumb for shutter speed is that it shouldn't be less than 1 / focal length. Well, that's straight forward on full frame cameras, but what about cropped sensor cameras? Is it going to be 1 / equivalent focal length? By equivalent focal length, I mean original focal length × crop factor.

My guess is: no, it's just 1 / focal length, cause the lens's focal length didn't physically change.

Answer

According to this Wikipedia article on the secondary effects of crop sensors:

The old rule of thumb that shutter speed should be at least equal to focal length for hand-holding will work equivalently if the actual focal length is multiplied by the FLM [focal length multiplier] first before applying the rule.

So, yes, use the 35mm equivalent focal length as your reference for minimum shutter speed.