Basing a reboot on the JVM makes little sense in this context.
That said, you lost me at "less ';' like in javascript".
As horrible as PHP is, it is really easy to sit down with PHP and a tutorial or a book and start banging out code that gives you instant results. PHP is like the MS Basic 2.0 of the web era -- people who aren't really programmers (yet?) can sit down with it and GTD right away -- their code may be ugly but they can see it working as they go. They don't have to learn what a 'WAR' directory is and how it is structured, they don't have to mess around with xml configurations, etc. The ubiquity helps, certainly, but IMO the reason it got ubiquitous is how easy it is to go from nothing to "hello web world".
I think a project that maintains this instant GTD environment but improves the language is actually quite a good idea, though I also think cutting ties with PHP by giving it a new name makes more sense than calling it phpreboot and once you involve Java it seems less likely PHP's context-free easy start-up will be maintained.
It lacks a coherent design philosophy; it's a collection of hacks; a house of cards with no style. It's full of idiosyncrasies that must be memorized because they make no logical sense. Put simply, it completely lacks taste.
Which at the end of the day is the most common benchmark of utility.
If the answer to all of the above is PHP, then you're going to get projects done faster there than you would in Python or Ruby.
You could say the same thing about ASP, or even ColdFusion.
I'd argue that those instant results had more to do with the higher availability of PHP on cheap web hosts, than the accessibility of the language itself.