I think and hope that it doesn't cost much more than Snow Leopard
My experience when I bought my late 2008 MBP was that in a few months they released New ones that fully supported 8GB of RAM and the audio out via the MiniDisplay port, and my MBP was crippled so quickly. The battery is replaceable and sucks, the improved ones got more and more battery life.
So for all the new features of Lion there surely will be some hardware limitations in the Macs released before Lion.
Lion is most likely going to cost 30 bucks. If you dont feel like spending 30 dollars in a few months then just wait.
I would be very surprised if Lion wasn't a free upgrade for the new MBPs.
If you need it now, buy it now.
If you can wait, wait. There will likely be refurbs of the refreshed models by then also.
I think is better to buy the full LION OS then going with Lion OS upgrade. What you guys think.?