I would see a 64 bit version, including an update for Linux.

Multiprocessor support should be asked from your OS developers.
If you meant multithreading, it is certainly supported by PhpED and this is used whenever needed.
64bit is not required until we get closer to 2GB limits in memory usage.
Linux won't be natively supported any time soon. You know, Borland has dropped Kylix and all the products developed with it are abandoned too.