The current version is 1.1. It is considered an alpha-quality release. go through each standard method and object and make sure the implementation actually works
The following items are on the roadmap, roughly sorted by priority:
Once that's done, there's always more stuff on the wishlist:
make sure exceptions can't crash the php engine. that means stop using call_user_func*()
implement regular expressions. Not a big deal, except for the regexp literals.
add support for unicode strings. Not very hard either.
add support for unicode identifiers. A bit trickier as it requires the lexer to be unicode aware.
add optional support for eval() and Function(). not a big deal if the parser is reasonably speedy.