I recently received an email from Christian Stocker, regarding my previous comments about Planet PHP.
After visiting again, I see that many of the PHP blogs that were missing have been added. It still uses blog titles rather than the names of people, but Christian promises to think about it. I much prefer the names, and it seems that Planet Apache and FOSS Planet feel the same way.
I also stumbled upon Marco Tabini's blog (RSS 2.0 feed), which seems to have been revived. This looks like one that should be added to Planet PHP, and I plan to keep up with it myself.