This is an unofficial native port of Pidgin to Mac OS X. It uses native GTK+ (www.gtk-osx.org) which provides better integration and does not require X11. It also comes with more plugins out of the box, including OTR.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.