A generic syntax highlighting tool for viewing online code?

I work with another project developer, and sometimes we communicate with them through IM. We can add files to Dropbox back and forth, but it would be nice to have an interactive version of the / google docs mouth where we could see the same code and edit it with syntax highlighting.

I know that Cloud9IDE has something like this, but I'm looking for a real simple, real-time (if possible), shared text field with PHP syntax highlighting. Does it exist?

UPDATE This is what I was looking for: http://collabedit.com/