So I'm aware of the big ammount of general-purpose scripting languages like Ruby, Python, Perl, maybe even PHP, etc. that actually claim being usable for creating desktop applications too.
I think my question can be answered clearly

Are there actually companies using a special scripting language only to create their applications?
Are there any real advantages on creating a product in a language like Python only?
I'm not talking about the viability of those languages for web-development!
Should I stick with C(++) for desktop apps?

best regards,
lamas
I have used a number of programs that were developed using scripted languages.  Several embedded device vendors ship my group Windows-based configuration and debugging utilities written in TCL.  Google's drawing program SketchUp has a lot of Ruby inside it (and users can create add-ons using Ruby).  I have seen many Linux applications written in Python.  There are many more examples out there, but often times finished applications are bundled up to the point where you can't really tell what's powering it on the inside.
Yes, there can be advantages to working with scripted languages.  Some scripted languages make it easier to do specific tasks; for example, text processing is much easier (IMO) in a language like Ruby that has regular expression support and a robust String class than it is in plain old C.  Generating a UI using a scripted language may make it easier to support multiple platforms, as all the platform-specific code is taken care of inside the language interpreter or pre-compiled libraries.  For example, our suppliers who build TCL-based apps claim they can build the UI for an app using TCL in a fraction of the time it would take them to build it in C++ or VB, and then they can port it to Linux almost effortlessly.
On the other hand there are a few things that scripted languages typically aren't suited for, such as writing drivers or doing anything that requires low-level hardware access.
Most importantly, however, is this: modern languages have become quite powerful to the point where choice of language doesn't make as big of a difference as it used to be.  Use the language you are most comfortable with.  The learning curve associated with learning a new language will usually have a much larger impact on your project.
"Real" and non-embedded use of Ruby, Python and their friends