to be honest though, with the advent of passenger (basically mod_rails), ruby webapps don't feel harder to deploy then PHP at all any more.

I don't see any practical reason to translate Ruby to PHP. Compared to other translations, this one doesn't make sense at all as you don't get any advantages of the translations result.

Compare this to a translator that translates Ruby to JS: Here you get the ability to run Ruby in the browsers. Or JRuby where you get the ability to run Ruby in a Java-only environment (plus a bit of performance in some cases), or IronRuby for the same reasons for the .NET platform.

But PHP? I don't get it.