When you install skype (which is a 32bit software) on a 64 bit Kubuntu 12.04 system from the official Ubuntu repositories, you find out that when you focus the skype window, the mouse theme changes for a classic KDE mouse theme.
That might be fine if you're using that mouse theme system wide. However, if you're using the default nice-looking KDE Oxygen mouse theme, you most probably find the cursor style in focused skype utterly ugly.
To solve this, remove skype from the official Ubuntu repos ('sudo apt-get remove style', if you have it installed, of course), access the official skype website, and get a "64bit" skype version for your Kubuntu 12.04 from there - http://www.skype.com/intl/en/get-skype/on-your-computer/linux/. By the way, the version on the skype website is the most recent, and the one in the Ubuntu repos is not.
Install the downloaded binary file, and you're done - skype is going to use your default mouse theme. That's easiest way.
Since the above-described way no longer results in a successful resolution of the cursor theme problem at least for Kubuntu 13.04, so here is how to actually make Skype use the default on Kubuntu 64bit:
sudo apt-get install ia32-libs
So what was the problem - Skype needs this dependency - libxcursor. Its 64bit version comes preinstalled, but being a 32bit app, Skype needs a 32bit version of the dependency.
Why install the package ia32-libs (which pulls in quite much stuff) and not just libxcursor 32 bit -- because for Ubuntu the lib is packaged in a larger package - ia32-libs. So you'll have to install the whole package. Anyway, that will successfully resolve the issue with the skype cursor theme.