There are a few. I have a PlayStation https://github.com/downloads/Catalys...PB-1_0_1_4.bar
emu and a SNES Snes9x for Blackberry Playbook: Official Thread - BlackBerry Forums at CrackBerry.com
and NES froggyface: FCEUXpb Playbook
They work very well. Touchscreen controls do not allow me to play Street Fighter type games, but BT controller support is coming (not sure when). Installing the em is as simple as sideloading, and running the device for the first time so it can setup up the directories. Download yourself a BIOS, get some .cue/.bin/.img files and you should be good to go. The only problem is that with the various games all different, depending on where you get them, troubleshooting can be a pita.
You can even get Win98 installed and running on your PB if you wanted to. They have Dreamcast, Sega Gen, N64, Game Boy Advanced, Tgraphix16, and a host of other ones available for the PB.
All the information you need is here PlayStation Emulator for PlayBook: PCSX-ReARMed-PB - BlackBerry Forums at CrackBerry.com