I'd say macworld 2009.
Macbook pro:
Don't expect anything major, as the design is good as it is. But for the sake of people's expectations of a redesign, it will most likely get the chicklet type keyboard of the MB/MBA. also, expect its lines to be more reminiscent of the MBA's. All this wrapped in an enclosure which is 10% thinner.
Macbook:
expect it to go aluminum by 2009. Also, the eventual incorporation of multi-touch, and backlight LED.