Indeed you can and it is also a useful function as you can change the state of a single bit with a single instruction.
Indeed it is an interesting command. I first learned of this 'trick' over on the AVRfreaks site. A caveat however is that it is limited to 'newer' AVR 8 bit processor chips and not on older ones. Not sure which Arduino compatible processors this would not work with, perhaps the Mega8 ? And of course any direct port access command will limit portablity between the various AVR chip types (168/328 Vs 1280, etc.).
PS: Grumpy, get with the times, things change over time. ;D