Self explanatory.  Does anyone know of a legitimate reason why this isn't on PSN?  I only ask because I really prefer to buy my PSP games digitally -- not to mention that once the Vita is released, UMD's will essentially be obsolete.

I dunno, but it's a damn good game.

Either Square-Enix don't want to release it on the PSN for whatever reason or it's just not available in your region. 
 
Edit: Looks like you're not the only one who wants it on PSN.

I have no idea why they don't release their back catalog either but I pretty much avoid buying PSP games on UMD. You get way better battery life on downloaded games.

If they did release Crisis Core on PSN I would heavily consider it. As it is, I'm debating whether to by Persona 2 on UMD or PSN. I'd prefer PSN but I would get the soundtrack if I bought it on UMD.

Square didn't put Kingdom Hearts on PSN when it was new so I doubt they are going to put up their back catalogue. I'd file this one under the "Japanese corporation doesn't understand the internet" category. 

And this is why the Go failed. Couldn't get half the decent PSP games in the store. So naturally, the pirates had a better experience with the Go. A 16GB tiny PSP that's easily hacked to run ISOs and Gameboy games is a pirate's dream handheld, especially at the prices they've gone for when they were cancelled. What a dumb move by Sony, made odder by the fact that they made some pretty good decisions in that era with PS3 exclusives and the 300$ Slim.