It's a program which will dump the bios and other files from the PlayStation 2 console via a host connection. It's useful for PCSX2, the PlayStation 2 emulator for Windows and Linux.
This program will dump the PS2 BIOS, DVD Player ROM, NVM etc from your PlayStation 2 via a 'host' enabled connection.
PCSX2 0.9.4 will be using the new format BIOS (*.p2b) created by BIOS Dumper v2.0, as it dumps a more "complete" copy of the BIOS. It is highly recommended that you redump your BIOS to get a more complete dump and thus enable PCSX2 to more accurately emulate the PlayStation 2.
You won't need to throw away your old BIOS files, as a convertor will be released in the future to convert the older format to P2B. Conversion is no substitute for a redump as converted BIOS's will not contain the new information dumped from BIOS Dumper v2.0.
The source code for this tool will be made available shortly on sf.net. For now grab the tools here and get dumping!