Apple's next OS update, SnowLeopard is going to provide a lot of support for GPU computing in the form of OpenCL. There's work under way for Windows support as well, but from what I hear, it's slower going without as concrete a timeline.

How that translates to computing cycles for applications like Lightroom remains to be seen. In theory, if they're using certain OS APIs (that are updated to use OpenCL) they may benefit without needing any updates. Fingers crossed.

One can count on Apple's own software to be optimized for OpenCL going forward. This should include things like FCP and its constituent applications.