Wow, would have never thought of that. So I did the search, and checked Automotive, and the locksmith I called, said that while they don't have the ability right now to do so, they might in a month or two, based on a newsletter he's received.
What he described though is an aftermarket key solution, so not a BMW fob replacement that he'd flash. He said basically he'd clone the existing working key to the new one, so the car would recognize either key as the same one. Not a perfect solution, but if it's half the cost of going OEM, and all the functions work, I might go for it as a second key.
I had a thought also, that I've seen just the key fob cases (with no guts) on sale on Ebay for $20, but he didn't think that I could put the internals from the new one into an empty case, which would have been great from an esthetic point of view.
You heard of this method? Sounds a bit like this, which this guy uses to flash a presumably blank BMW key:
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