a IV-iv part in a progression might be considered Deceptive. The way it works is that the Major third (in this case, F#) is going chromatically down for chromatic movement (F# - F, then most likely to E in the next chord)

That's how I'd use it. I come up blank with any terms from my theory classes, besides modulation (which it could be, read the posts in the modulation thread).
Its just a parralel Modulation so that the 3rd of Chords IV and iv resolve to the 5th of chord I.
- Satch is awsome -
Wake Me When September Ends has the same thing going on (C Cm G).

Seems a bit odd to me to call it a modulation. Which I always thought was a temporary change of key. Seems strange to think that you could do a little temporary change of key every damn verse. But its been a long time since my theory classes. I guess that's the question: how short can a modulation be, or how often can it occur, and still be called a modulation?
There is a specific name for this, but I don't recall it off hand. I have a book on chord progressions that covers this in an entire chapter, but I am at work and don't have it available.

This is actually fairly common. I recall it in Where is my Mind by the Pixies, The Decline by NOFX and I'm so Lonesome I could cry by Hank Williams. If I remember, I'll take a look tonight and update this thread.