Interesting.
At one point, we were planning to open source our gaming framework and build business around server-side functionality. However, after various discussions, I finally abandoned that plan and we are focusing to use it internally.
First, in games particular, considerable amount of work is spent on the client side. Unless you are super-successful to encounter serious scalability issues, all the hard problems are on the client-side.
Although gaming companies do not currently have that much back-end guys, they still have quite capable coders in general, who can learn back-end stuff quite easily. Thus, you really need to provide significant value to them (us). Looking through your APIs, you currently have solved some basic authentication stuff. That's okay as a start but definitely not enough to attract skilled teams.
Second, game business is very hit-driven, thus you are likely to serve the less-profitable long tail developers. The best offering for them is not to provide server-side technology per se, but bring more buyers/players for their games. Thus, approach that e.g. OpenFeint has taken seem to serve those guys better, they basically are offering the stuff that you offer + the existing community.
But best luck! I suggest that you talk to experienced game studios. Find out what are the biggest pain points and try to provide solutions to those.
EDIT: Note, I didn't want to sound discouraging, although reading it now, it definitely came out like that. I think there's definitely opportunities in this space, I just wanted quickly to highlight some key issues. Note also that it will be a very competitive space, because successful mobile multiplayer game companies can also try to enter the space with their proven propriety solutions. That's part of our long term plan, i.e. we first try to create succesful mobile multiplayer games, and then consider platform-provider option again.