It is not possible to install Skype, Google Earth or any 32-bit application in Linux Mint 14 RC 64-bit.
Cause of the problem
The ability to install 32-bit applications in a 64-bit environment is commonly referred to as “Multiarch”.
An upstream change occurred in Debian’s dpkg which made the Multiarch configuration in Ubuntu obsolete. That configuration was removed and Ubuntu 12.10 consequently released with Multiarch disabled by default.
The problem wasn’t detected during QA and impacts the two 64-bit editions of Linux Mint 14 RC.
For more info on this issue: https://bugs.launchpad.net/ubuntu/+source/ia32-libs/+bug/1016294
To enable Multiarch, open a terminal and type the following commands:
sudo dpkg --add-architecture i386
This issue will be fixed manually in the stable release of Linux Mint 14.
In an effort not to conflict with a future upstream fix from Ubuntu (which is likely to provide /var/lib/dpkg/arch in an update to the dpkg package) it was decided not to re-enable Multiarch on the user’s behalf via package updates in Linux Mint 14 RC.
In other words, if you’re running the 64-bit RC of Linux Mint 14, please apply the workaround. If you’re planning on waiting for the stable release you don’t need to worry about this issue.