The PHP-GTK Community website has posted the results of their PHP IDE survey (2007) that's just wrapped up:

Following a two-weeks poll, a first for the community site, the results for the development environment used by PHP-GTK developers are in.

The top three spots on the list were a close run - Eclipse topped the list with 30 percent followed by the generic "simple editors" option at 26 percent and Zend Studio at 25 percent. The rest of the options (well, besides PHPEdit at 4 percent) were at 3 percent or lower in representation. Check out the post for the graph of the outcome and some of their own commentary on the results. Also, check out this page for the full results from the poll.