I couldn't find any, but here's an explanation of the input format, with some example snippets:

http://code.google.com/apis/predict/docs/developer-guide.htm...

It's pretty straightforward.

Here's one: http://code.google.com/apis/predict/docs/language_id.txt

Linked to from this page: http://code.google.com/apis/predict/docs/getting-started.htm...