When PDT 2.0 is still slow and DLTK 1.0 hasn’t reached final milestone, Zend guys are using unreleased PDT 1.0.5 in their Zend Studio 6.1. Most important thing is ZS is based on Eclipse 3.4 (Ganymade) and prior PDT 1.0.x builds worked only with 3.3 (Europa).
You can get it in 2 ways – first is to compile it from CVS according to these instructions and the second is just to download Zend Studio 6.1 and copy /features/org.eclipse.php* and /plugins/org.eclipse.php* to Eclipse 3.4 installation.
Update (17.11.2008):
PDT team have officially released 1.0.5 build for Eclipse 3.4. You can get it directly from download page.