Ubuntu has, as expected, dropped support for Ubuntu 10.04 LTS. Thinking that 2 years is too short for something called "long-term support," I visited https://wiki.ubuntu.com/LTS to see what the deal was. First, they erroneously claim the 10.04 Desktop will be supported through 2013. Sorry, my laptop says it's no longer supported, and when I do an apt-get update/upgrade it very clearly tells me I am no longer receiving security updates.
They also say they are going from 3 (they clearly mean 2) years to 5 for LTS, which is a good move, but came too late to avoid my blowing away yet another Ubuntu system for Linux Mint.
Added a dozen hours later, after reading some fine print regarding the Linux Mint 13 RC at http://blog.linuxmint.com/?p=2010, I thought I would point out yet another thing the Mint team is doing more intelligently than we've become accustomed to from the Ubuntu folks: Linux Mint 13 is also an LTS (Long Term Support) release and it will be supported until April 2017.
Fours years is good. Especially as compared to two.