Not if we're talking about the real world (implementation), rather than the theoretical capability of a language in itself. Perl and Ruby don't see much love on Windows, particularly with GUI toolkits and the like. Python is the only one of the three that feels comfortable using on Windows, from the skeleton of the app down to actually distributing it.
Java is really good at cross platform apps though.
This is one of the few things that irks me in programming communities, often you'll seen criticism or praise of a point in a language, and then some language lawyer comes and talks about what said language can do in theory, rather than looking at the practicalities of actual, real world implementations, the community and culture surrounding it and so on. No one gives a crap if any dynamic language COULD be made to work the right way on many OS, people care if the work is done, not if it COULD be done.
The worst offenders are of course people victim of the sufficiently smart compiler curse.
This is what I was wondering about, because I have so far failed to install a single Python package on Windows without it breaking on some Unix dependency.
If you're pulling a pure python package (like Django, Tornado or requests) then you're golden on any platform python is available for. If you're pulling a python package that contains C bits (like PIL, msgpack-python) then you'll need the compiler toolchain and associated libraries.
Luckily, most such packages (the popular ones at least) can be obtained in other ways (PIL through a win only download, or get a pure-python alternative like msgpack-pure-python).
I use Ruby for light scripting on a Windows machine. RubyInstaller worked just fine and so do the irb shell and my scripts. Dropbox is a web app, so who cares about GUI toolkits? Perhaps you're right that the Python community tried harder, earlier, to support Windows and other non-UNIX platforms. But it's hard to imagine Dropbox actually selecting Python to build their web app for that reason. Maybe in their earlier days they used a hosting service that supported Python but not Ruby, Perl, etc.? Who knows...
You wrote 513 characters about a subject you don't know anything about. Why is that ? You didn't use dropbox, you don't know how it works (hint, what made it so popular is the desktop client that syncs your data in the first place. And it's written with wxpython.), but you felt compelled to write 513 chars about your ignorance and wild speculation ("Maybe in their earlier days blabla").
Then comparing apples to oranges "I use Ruby for light scripting" vs "widely deployed desktop app with users from the three major desktop systems (Windows, OS X, Linux)."
This kind of behavior is a serious annoyance in online discussions.
I'm sorry if I annoyed you, but there's really no need to be rude. It's a subject I never claimed to know a lot about, but it's also false to say that I don't know "anything" about it. I'm here to learn more, not to show off what I already know.
If you were actually here to contribute, you might give a concrete example of why Python is more cross-platform compatible than other interpreted languages (because someone built a better Windows GUI toolkit for it?), but if you just want to put down and feel smarter than someone you don't know, you're wasting your time and keystrokes.
The fact that you actually bothered to count how many characters I typed strongly suggests the latter.
Dropbox also have a desktop client that's written in python. Presumably with a slightly different UI layer and packaging method depending on the target OS, but with the underlying functionality shared.
This is one of the few things that irks me in programming communities, often you'll seen criticism or praise of a point in a language, and then some language lawyer comes and talks about what said language can do in theory, rather than looking at the practicalities of actual, real world implementations, the community and culture surrounding it and so on. No one gives a crap if any dynamic language COULD be made to work the right way on many OS, people care if the work is done, not if it COULD be done.
The worst offenders are of course people victim of the sufficiently smart compiler curse.