Apparently it’s not a wise idea to be an early adopter with regards to the Blu-ray high-definition movie format. Due to competition from the HD-DVD format, the Blu-ray specification was released about a year early. Smart shoppers will wait until players are available that support “Profile 2.0” of the spec. There’s also an intermediate step called Profile 1.1 (current players, with the exception of the PS3, support Profile 1.0).
Update: Ars Technica has an article that explains more about the various specifications and the players that support them.