I would very much appreciate to attend the phpdoc meeting at LinuxTag. Goba, sorry for disappointing you: the potential tool for editing DocBook has been written by Christian Stocker ;) Have a look at http://www.bitfluxeditor.org.
Hm, I have checked some demos on oc4 which were capable of online docbook editing. Those were not that cool looking like bitfluxeditor though.
Although, I am sure Christian would admit that it's not ready to be used for WYSIWYG editing of the PHP manual yet - it's a good tool I would definitely take into account when discussing at LinuxTag, because it allows browser-based (Mozilla only) editing of XML in WYSIWYG mode (XML transformed with CSS), or the XML source.
It looks cool, I just can't see the cursor ;)
Looking forward to our meeting ;)
Goba