Fred Himebaugh links this news item about a pretty new phenomenon: the increasing popularity of the increasingly complex and large-scale orchestral music of computer games. Game music has come a long way since those cheerful little "beep beep boop" ditties that accompanied the cartoons that displayed in between every couple of levels on Ms. Pac Man.
I really don't know a whole lot about game music, but it does receive occasional notice in film music circles. The big hitter right now, in terms of game music, is the stuff from the Final Fantasy series, composed by Nobuo Uematsu. I own one compilation disc of this stuff, and I don't recall liking it all that much, but I'll try to give it another listen one of these days. Another big name is Mamoru Samuragoch (Japanese language site), a deaf composer who was actually profiled by TIME Magazine a couple of years back. I own Samuragoch's CD Sounds of Onimusha, which I like quite a bit.
On this side of the Pacific, the big name in game music (so far as I know) is probably Michael Giacchino, who has more recently started to break into the mainstream of film and TV scoring with work on The Incredibles, Alias, and LOST.
As I note above, I haven't really explored game music at all beyond the two, count 'em, two CDs of the stuff that I own, but the idea of orchestras putting on concerts of game music does not surprise me in the slightest.
Now, if we can just get the Buffalo Philharmonic to host an installment of the Lord of the Rings Symphony....