Munin-alert-hipchat is a project mainly written in Perl, it's free.
Send Munin alerts to HipChat
This script converts Munin alerts into messages in a HipChat room.
Put this script somewhere on your Munin master and make it executable. Then add it as a contact in your Munin configuration like so:
contact.hipchat.command | [THIS] [THIS] --room=[ROOM] --token=[TOKEN]
contact.hipchat.always_send warning critical
Replace [THIS] with the full path to this script (yes, it is supposed to be there twice). Replace [ROOM] with the name or ID of the room where you want the messages to arrive and replace [TOKEN] with your HipChat token.
Don't forget to add it to your contacts list.
If you want to change the name associated with the message, pass a value for the --from argument. If you'd like the messages to link back to your Munin web interface then use --munin-prefix.
If you need to put spaces or other "special" characters in a from or room value then you can use URL encoding. e.g. %20 for a space.