Based on a post from the Eclipse PHP newsgroup, the ThinkPHP blog has posted about the possible integration of XDebug with the PHPEclipse project.
They also make mention of the two Eclipse projects in the PHP community - the Zend PHP-IDE project and the older, but still being developed on PHPEclipse project.
PHPEclipse currently seems more open to community contributions than Zend's PHP-IDE project. On the other hand Zend's working more closely together with the Eclipse Foundation on the PHP-IDE project than the PHPEclipse project does.