As you might recognize from the name, it was developed by the team behind the PS One emulator PCSX.

What's New in version 0.96:

• Huge rewrite, mainly from the new members of the Playground branch! Too many speedups, optimizations and other fixes to write here! Many famous games will now work.
• Dropped VM build replaced by the all new Vtlb, meaning no more 'Cannot allocate memory' errors at start up, more accurate emulation, slightly lower speeds but with many optimizations to come
• Full memcard support, working in all games
• Improved Frameskip/VU-skip
• Special Game Fixes Section
• Advanced Options Section for custom tweaking VU/FPU behavior.
• Rewritten Multithreaded GS (MTGS) mode, with as much as 15% speedup for HT machines (only 3-5% for Dual Core), and fixes many instabilities.
• Improved VU/FPU Flags and Clamping support (helps fix odd behaviors and SPS in some games)
• Improved EE/IOP synchronization (fixes many freeze-ups and vmhacks).
• Improved CDVD support.