I would guess Post-Spring with a better graphics card and maybe new processor. It would be nice to see a BluRay drive, but that will go in the professional desktop first.
blu-rays still way too expensive and not viable for Apples computers. apple's record profits are associated with offering a smaller, more efficient (to produce) computer lineup. manufactoring costs associated with blu-ray need to make a serious efficiency jump/price decrease before consideration is even made for offering one.