I've been pondering this very same issue. The main reason not to buy Blu-ray now is that there just isn't all that much content you might want to buy.

There are some other annoying reasons not to buy Blu-ray today. There's something called Blu-Ray Live (Profile 2.0) which requires an Ethernet jack. Today, only the PS3 has the potential to support this. All the other players don't have it. Conversely, the PS3 doesn't support "bitstream" audio output (see Engadget HD discussion), which means that you can't play discs with DTS-HD audio encoding, since the PS3 isn't smart enough to pipe it through the HDMI jack to your state of the bleeding art receiver.

Grumble.

Since my current DVD player is only "progressive" and has no HDMI output, I'm actually tempted to get the discount blowout on the HD-DVD players (Amazon link). $129 gets you a player that will upscale existing DVDs, and you get five free HD discs (from a total library of just over 500 and that's it, ever). That's enough to have some "HD pr0n" to show off my system, yet improve the quality of the regular DVDs that have content I might actually want to watch.

Never mind that we hardly ever watch DVDs. Instead, we tend to snag movies in HD with the Tivo. Still, I've been increasingly annoyed that TV-aired movies tend to make all kinds of cuts for time and to bleep out obscenities. It's almost comic how bad the dubbing has been done. That's incentive to get the movies on real DVDs. Hmm...