Vim-dbgpclient is a project mainly written in ..., it's free.
Hadi Zeftin's updated version of DBGp-client updated to run under 7.1 and pathogen
A Vim client to connect to Xdebug was originally written by Seung Woo Shin <segv sayclub.com> remote PHP debugger which was then developed by Sam Ghods <sam box.net> and renamed DBGp client
In 2009 Hadi Zeftin updated the script to run under 7.1 and added tab support DBGp-client
And this is Hadi Zeftin's version updated to run using pathogen.vim