I thought I would build EMC2-simulator on 64-bit Ubuntu 11.10 following the instructions from the wiki. To get the source and dependencies:
$ git clone git://git.linuxcnc.org/git/emc2.git emc2-dev
$ cd emc2-dev
$ cd debian
$ ./configure sim
$ cd ..
Then install all the required packages with "sudo apt-get install". dpkg-checkbuilddeps suggests installing tk8.4 and tcl8.4 but I found that in ordet to get the configure-script to run without errors I needed tk8.5, tk8.5-dev, tcl8.5 and tcl8.5-dev, and I removed all the 8.4 packages of tk and tcl. That makes configure run without errors. Then try building:
$ cd src
$ ./configure --enable-simulator
However that produces a number of linking errors. Don't ask me exactly why but this patch: 0001-changes-to-make-sim-build-on-ubuntu-11.10.patch.tar (updated corrected version!) seems to fix things, and I get emc2 sim built and running. Just in case anyone else wants to build on 64-bit Ubuntu 11.10.