After uninstalling the Content Translation and Locale modules, the `language` columns for the nodes and fields tables remain at any language that was saved while supporting multiple languages via Locale. Nodes that were never saved with a language continue to work.
When these modules are uninstalled, the original "source" node should be reset to 'und' language to ensure the content is still working. Either this, or at least there should be an option or warning expressing this potential problem. If a user uninstalls these modules after using them for a while, any of that content is now unusable.