Answer to: Replace HDD with SSD in MacBook Pro - late 2008 model?Yes you can even use up to the latest SATA 6 gb/s SSDs but since your Macbook Pro supports only up to SATA 3 gb/s, the SSD will not be used at its full potential. However it will still be a vast upgrade in responsiveness of your machine.
Answer to: Can I upgrade CPU and HD (SSD!)?As of this moment I believe OWC are making Sandforce based PATA SSDs for older Macs. I'm not sure if it is worth the price tag but I have installed one on my iBook G4 and it does make it much much faster. Its pretty amazing.