I created #madisonphp on Freenode. I'm not sure if we'll reach a critical mass to keep it going but I figure it is worth a shot. :)
If you are interested in joining but have never used IRC, are new to IRC, or in any way need help getting setup please feel free to find me on Twitter @beausimensen or email me directly and I'll see what I can do.
To get started quickly you can also join using webchat by visiting:
Choose a nickname and enter #madisonphp for the channel and you should be good to go!