Lisa Shock, who runs Monster Rancher Metropolis and deals directly with Tecmo posted to the site that the game ships from the factory today and should be in most stores within a week. Apparently Gamestop and EB pick their copies up from the factory and do their own shipping, so preorders with them should be faster.
My wife is nearly through Prince of Persia: Sands of Time and now I'm not so sure that Sphinx and the Cursed Mummy will be getting a spin before MR4 shows up on our doorstep and we're jockeying for who gets to use the PS2. Fun (but expensive) couple weeks to be a gamer!
here's the cheap import stuff: http://www.toysnjoys.com/closeout_psximport.html and here's the (expectedly) more expensive brand new stuff: http://www.toysnjoys.com/psximport.html oh and a dance-specific page: http://www.toysnjoys.com/konamimusic.