I'm wondering if the 360 does indeed get HDMI eventually, there will be additional updates to enable DD Plus or True DD for the 360's multichannel positioning outputs. multichannel audio transfer encoded by DD or DTS over SPDIF is frowned upon because they are lossy. SPDIF can only have enough bandwidth for 24bit 192khz PCM for the stereo channel only at best. If the 360's HD-DVD add-on will have visual fidelity equal to that of dedicated players, but skimp on audio capabilities (SPDIF as opposed to HDMI) then I'll have to buy the Toshiba player instead just for that. SPDIF has been useful, but it's time for it to go. SPDIF was never the best technology for audio fidelity when it was first introduced either. (beaten by vinyl still, and even within the digital domain, I2S is still superior.)
For those of you who have LCD monitors and such, DVI-D or HDMI is the way to go. 1:1 pixel matching is the biggest advantage of HDMI.