Discussion of this issue a the bottom of this page. But here's the link in case it's gone off the bottom by the time you look.

Here is a link that might be useful: Controlling rosemary

It might have rooted. Why don't you have a look? But you could just cut the thing back. Much less work than digging it up and fiddling about with transplants. You could cut yours by half easily and it wouldn't mind at all.

You can cut it back to about 1/3 of what it is now. First check to see if any of the lower branches have rooted in. If so, you can cut them from the mother plant and pot them up or put them directly into the soil.
You do realize that the rosemary is happy, and will grow back to an unmanageable size again unless you constantly prune/harvest it? Your garden is obviously a great spot for the rosemary, as well as other plants!
I think you are in need of some rosemary recipes. If you want some, e-mail me and I'll send them along. Don't want to hijack your post with recipes!