I was chatting with some friends last night, trying to explain the scoop on Blu-ray profiles, but I’m not sure I did a terribly good job of it. I've just come across an article at C|Net, though, which does explain Blu-ray profiles pretty well.
(The short answer, though, is that Profile 2.0 is the final one and, if you’re going to buy a Blu-ray player, that’ll be the most future-proof.)
And if you were to get a Blu-ray player, I can also recommend this comparison chart at AVSForum as a good starting point—ostensibly, it’s a table comparing the audio capabilities of various Blu-ray players, but it actually does a good job of summarizing things in general.
In the case of that table, the short answer is that you’d want to get a player with the green-colored cells all the way across its line in the chart. As I write this, and of the players that are currently available, that narrows things down to Panasonic’s DMP BD-55 (the Blu-ray player I have) and Sony’s BDP-S550.