Just for information. I'm running Mint KDE 13 with Kubuntu backports repo installed. On a dist-upgrade today, I was upgraded to KDE 4.9.2.
On another note. Using the cube desktop effect on my netbook, if I uncheck the show caps option on the advanced tab of desktop cube in the desktop effects section of system settings, the cube really gets speeded up. I would be interested to know if this works for anyone else.