To begin: I understand why you're asking this. You're looking for a way to create better applications, faster. That said, discussions of programming languages are almost as fraught with disaster as discussions of text editors. I make no judgement on the choice of language being asked ; if you'd like, replace 'PHP' with
'Haskell' or
'Effiel' below (Yes, those are programming languages). A fair bit of the reasoning here is
my opinion, but the end decision is not. Now, as for whether or not there is a plan to support PHP in the Netburner environment...
There is not. PHP is a very complex language with a fairly large runtime which would make porting it challenging to say the least. Furthermore, I doubt that porting the language itself would provide much utility, as the only real value that PHP offers is the shear volume of libraries and frameworks built for it, and I'd be very doubtful that those would work with a minimally ported implementation.
Finally, on Programming Language level, I present this:
PHP: a fractal of bad design. I do understand why you want to have an additional, higher level language to use, but to be honest, I'd be very doubtful on ever seeing PHP chosen. Python? maybe, I'd love to have it, but it's unfortunately a) large, b) relatively slow, and c) RAM intensive (minimum 4-8 MB per runtime). Perl? again, maybe, but it's a) large and b) generally requires being compiled.
In short, the effort to port PHP to the Netburner environment is large for a language that is mediocre and whose performance in the environment is questionable. This leads to the conclusion that it is best to spend our efforts on developing other areas to better serve the broadest base of our customers in the best manner possible. I'm sorry that we haven't/won't be going down a road that you appear to desire, but that's the reality of it. :/
We do have a version of Lua (version 5.10, if memory serves correctly) ported and available for scripting support. It has the significant advantage of being a) small (in RAM and flash, both < 200k) and b) fast. It can also call native C functions with a very minimal overhead (roughly one operation per argument).
-Dan