I'm in two minds on this.
The Halo series was released as a set of books. The book that actually covered the events of the game felt really stiff, I expect mainly because the writer couldn't venture too far away from the story from the game.
The other books weren't too bad story wise but there was absolutely no proof reading whatsoever, and it seemed no editing had gone into it at all.
Another game close to my heart is Metal Gear Solid which has also been novellised (is that a word). While I haven't read it I have been told by a fellow fan that it also feels very stiff and that they don't do much to flesh out the characters feelings and that most of it almost seems copy pasted from the gaem script.
So, while I would like to see some games released as books, I would possibly be setting myself for dissapointment.
That being said:
Left4Dead would make an interesting book
Some of the Resident Evil series (I think they have been done.)
Farcry/Farcry 2
And for randomness sake:
The story about how a dumpy italian plumber ended up in Mushroom kingdom and scored with the hot princess