I think you'll struggle to find anything very like PHP that is perfectly suited for desktop GUI apps. Languages like PHP show their "script-behind-a-webpage" heritage just in the way that awk & perl are very much suited to general purpose/admin scripts on unix boxes.
There are GUI bindings (tk, gtk,...) for many languages - included "interpreted" ones that are closest (but still not that close) to php. Obvious examples would be python, ruby, or perl (though I'd greatly recommend one of the first two).
However, none of these are really geared towards desktop GUI apps, and it shows. Languages such as Java are far more suited to this sort of thing, but are quite a big step language wise.
If you're on a windows system I'd recommend c# with mono. I think it's more important to use the right tool than going for something close to PHP.
Don't even consider VB