As I said, the Wii is the only device I know of with a slot-loading disc drive that will accept mini discs. The vast majority of slot-loading drives, such as, I'm assuming, the ones the PS3 uses, not only won't play a mini disc, but will be really screwed up if you even just stick a mini disc into them. Sony's not going to use a format for the PSP2 on the basis of compatibility if it's not even compatible with their other game console.
Sony had no qualms about releasing the PSP with the UMD format which was incompatible with the PS2 (and also PS3). So you can't discount the possibility just because the PS3 won't accept Mini-BRD.
Even if the PS3 won't (I'd like to see some conclusive evidence of that too, btw) accept Mini-BRD, most other BRD players will. And who is it that is behind the BRD format and wants it to succeed at every cost? Why, Sony. That's who.
The UMD is a failure, and I can't see Sony maintaining it in the PSP2. I suppose it is possible they might make a UMD 2.0 format. The benefits that would offer is 1) No one can burn UMD discs without Sony's authorization, and 2) it would maintain backwards compatibility with the original PSP library.
So that's something they *might* do. But why bother? BRD is their flavor of the month. They need to make it Mini-BRD though, because of the fact the PSP2 is a portable. I guess its possible it could be regular BRD...
I'm looking at this from all angles and trying to figure out what Sony would think is the best way to go. I've narrowed the possibilities down to these:
1) Mini-BRD
2) UMD 2.0
3) Regular BRD
They *could* reject optical media and go with flash media like the DS uses, or just rely on internal storage via downloads, but those routes are very wise and logical, and that's why I kinda doubt Sony would pursue them. So I'm stuck with those 3 choices above. Which one will they do? I guess it won't be long til we find out... Anyone want to place bets?