Yes, though with the original firmware at least, there were two known issues:

• Due to a bug, battery life was slightly worse with no SIM than with one. That's likely been fixed in later firmware, but I've not seen confirmation of that.
• Nokia Messaging could not be set up. I don't expect that's changed, but the email application works the same as with a SIM otherwise.

EDIT: Oh, and you'll have a small, white SIM icon with a red line through it in your status area all the time. If it bothers you, you can likely replace that icon with a blank one easily enough, though I haven't investigated that.