Can I move mature gardenia bushes?

I have 2 (at least, there may be more) gardenia bushes that grow gangbusters every year, and have to be trimmed back. This wouldn't be a problem if the previous owners hadn't planted them right in front of a window.
They are gorgeous and grow by the foot yearly. My hope is that I can transplant them to a new location (similar to where they are now) and let them grow to their hearts content.
They are just now getting small buds on them. Any suggestions?
I am in zone 8.

You can move them.
The issue will be when and how.

Moving when they are most dormant would be best, so late fall or winter.
Take as much of the rootball as possible.

I would root prune them about two months before that- just insert a shovel all the way around as if you were going to dig them out but stop well before getting underneath them. This breaks a good portion of the roots but leave enough of the root system intact to nourish the plant. The severed roots then begin to regenerate and will be ready to take over in two months when you actually lift the plant and sever the rest of them.

Have a tarp ready when you lift the plant so you don't have to manhandle or drag the rootball.
It is best to do the moving on a cloudy day with rainfall predicted. Keep them well watered afterwards. If they are going into a particularly sunny spot a temporary shade structure can be easily constructed with a few bamboo stakes, a sheet, and some clothespins. You can remove it after about two weeks if all else looks good.

Moving about any shrub is a similar process. At the link below, I offered some tips for moving an Azalea, but would offer you the same advice.

http://davesgarden.com/community/forums/t/1247246/

Thanks guys! Great advice!

Would either or you suggest pruining it back anytime prior to moving? If so, when?

As suggested above, ROOT prune well before you start the move. Deep cut into the soil around the plant, no more than about 1/4 of a circle at a time, then give it a month or so to recover, then do another part of the circle.
What you are doing is forcing the plant to start new roots closer to the plant so that when you dig it up it already has some new roots started in the volume of soil that you are capable of moving.

Each time you cut some roots, cut some of the top, too. Basically pruning it back, because where the roots are cut they can no longer support that much top growth. Good opportunity to clean up the plant, remove broken or dead branches, shorten some over-long ones, and reshape the plant to be more symmetrical. DO not go charging into it and do major pruning, though, just enough to balance the amount of root loss when you prune each section.

The end result will be a smaller root ball that has some new roots, and is a reasonable size that you can move.
That root ball will be able to support the reduced top, even if some more root damage is done during the move.