There is potential for confusion when configuring the Preferences > Titanium > "Titanium SDK Directory" field, because strictly-speaking this directory contains the Mobile and Desktop SDK directories (mobilesdk and sdk respectively). This problem is especially the case for new users, who aren't familiar with our file structure.
Rename this field to "Titanium SDK Home" or "Titanium SDK Home Directory", to reflect Configuring Environment Variables.
Also rename "Android SDK Directory" to "Android SDK Home", for consistency. There are references to this term in google, although admittedly I cannot find it on the Android Developers site.