+5
How about adding a php runtime just like kodiak?
Add php runtime to allow running php scripts locally. I have kodiak installed on my ipad which does just that. Textastic could benefit.
Customer support service by UserEcho
Textastic offers syntax highlighting for many languages, but it doesn't include compilers or interpreters due to restrictions of iOS.
There are apps on the App Store that can execute code: Python for iOS, Codea, Kodiak come to mind. But due to the same iOS restrictions they can't offer code sharing features like FTP, Dropbox or "Open In".
Also have a look at Kodiak's FAQ section at http://www.becomekodiak.com/faq.html