There's two new posts that look at an up and coming PHP IDE (really a PHP plugin for an existing IDE) - NetBeans - one from Mike Borozdin and another from Juozas Kaziukenas.
Here's some of Mike's comments:
And some thoughts from Juozas:
I find more more articles about NetBeans 6.5 IDE for PHP, for example this Mike's article. Why people like it so much? After some weeks spent reading all these articles, I finally decided to throw away all other editors and try new-and-shiny NetBeans. [...] Overall it's just a wonderful tool - stable, helpful and being actively developed. Give it a try!