No -in Ubuntu-64 the ia32libs are not there by default, I had to install these separately as well recently!
I went back and checked with my installation of Ubuntu 10.04, the last LTS version of Ubuntu. I see that at that time, ia32-libs was still included by default. Since Mint 11 is based on a later
version of Ubuntu (10.10? 11.04? - whatever) it would seem that both
have seen fit to stop including this compatibility library.