I'd forgotten about this until I saw a post about it on a local linux user group mailing list. The gist is to run:
zdump -v America/Denver | grep 2007
for whatever timezone you are using. You should see Mar 11 in the output, not April something. Most recent Linux distriubtions should have this updated (specifically the libc updates) so as long as you're keeping your system up to date you should be okay.