I suggested 5.3.0 because of Object Oriented programing benefits. As a developer, I can't take advantage of the new tools PHP brings to us because on the PHP min requirement right now. I love bring new features, but I can't do that if I am forced to PHP 4 users. I might be moving all my plugins to at least 5.2.x and that would cause upgrades

It would be nice to get a full API reporting system so we know what most WordPress users are using for PHP versions overall. I think though a lot of the pluging authors, are moving towards Object Oriented class based systems. I done now two plugins and converted my theme to a class based system and the benefits for organization have been incredible.

PHP 5 would also get rid of globals. A huge issue. Just food for thought.....