I recently was forced to upgrade Skype on my work desktop, which is stuck on Ubuntu 10.04 LTS, in order to continue signing in. Version 4.0 is no longer supported. They only provide 32-bit builds of 4.3.0.37, so I had to jump through a couple hoops to get it running.
First, download the latest "Dynamic" build from the Skype website. Extract this tarball this in a location of your choosing. Link the resources to the right spot:
$ sudo mkdir /usr/share/skype $ cd !$ $ sudo ln -s /path/to/skype-4.3.0.37/*/ . $ cd /usr/bin $ sudo ln -s /path/to/skype-4.3.0.37/skype
If you try to run skype at this point, it complains about missing libphonon4, even if you have it installed. You need a 32-bit version. This issue can be solved by following the directions in this bug report.
Happy Skyping!
