Agreed, we upgraded our main site to 2.0, but many of the support classes are still 1.1. If we do need to make a tweak, it's been easier to just do it in 1.1, since there is no major push to upgrade.
Also, we have a winforms app, and to get users to 2.0, boy, that would be scary. Our new installs ship with .Net 2.0, but all the code is 1.1. (That way those users will be ready for the upgrade.)