According to this note from the International PHP Magazine website, there's a new tool being offered by Aivosto that allows PHP developers to "reverse engineer" their code back into flow charts and UML activity diagrams.

Visustin is the ideal diagramming tool for software developers and document writers. Save your documentation efforts by automatic charting! Visustin reverse engineers your source code and visualizes it. No manual drawing is required. Your existing code is all you need. If you see a real complex case, print it out as a big mosaic and hang it on your wall.

Functionality includes the automatic creation of a optimized layout, the ability to do a multi-page printout, saving the graphs/charts/etc in various formats, run a "bulk chart" on all of your files at once, and export options including PowerPoint, out to the web, and Word.

You can get the full details on the product (as well as screenshots and a demo) from their website.