But mini brd's would work in a regular BRD player and a PSP2, that is already much more support. HD movies on the go, but probably no special features on the mBRD.
Movies started off pretty good on UMD and died off quickly when Sony didn't follow up with a standalone player that played DVD's and UMD's. You are right, who wanted a movie that only works on a PSP. mBRD shouldn't have that issue as it is a BRD that would work in a regular BRD player. I'm sure all BRD players can be firmeware upgraded to make the laser look for smaller disc than usual assuming that it reads from the outside in.
I honestly wouldn't be mad at Sony for going that route as it not only differentiates the PSP2 from the DS2, but it will make the PSP2 expensive and take it out of the same market as DS once again. It will once again be the High-end handheld, and to be honest, that is PSP's corner of the market and they should stick to that. PSP is the most successful competitor to a Nintendo handheld ever and they did it being the High End handheld, so the might as well stay on the same track and improve on past failures.
Like I said b4 I think UMD was a good idea at the wrong time with the wrong medium.
But mBRD's need to be free standing disc like GC disc and not cartridged like UMD.
It could be like the convergence of the minidisc and the UMD formats as soon as they make BRD burners affordable.