It looks like this was talked about in relation to the N900, and it appears that apt-X is definitely a no-go. A few Android products have shipped with apt-X support, so depending on exactly how the implementation of that works it might be possible to lift the binaries from one of those - I wouldn't get your hopes up though.

The chances of Nokia adding this officially are basically nil - the last firmware release is almost complete and isn't going to be adding any significant features. Contacting anyone at Nokia about it is probably a waste of time. :|