The frame node only outputs the current frame number. It's a variable.

I posted some examples of animated materials (with illustrations) in an earlier thread:

http://www.renderosity.com/messages.ez?Form.ShowMessage=994366#7

As an experiment, variable nodes were used to determine the rate at which the Blending value changes, but it's usually easier to click the little key-symbol next to the number and manually keyframe the changes.