The version 1.3.1 update for the free iPhone app:
is notable for the single item listed in the “What’s New in Version 1.3.1” note:
minor bug fixes for iPad compatibility.
This is the first app I’ve seen with an update specifically for compatibility with the iPad.
After searching around a bit, I also found this 99 cent app that notes it can: Remotely control the iPod player in your iPhone, iPod touch, and iPad).
FYI: I don’t know if this app will have to change its name, but its release (Dec. 29, 2009) pre-dates Apple’s iPad announcement. So, it should, in my opinion, get to keep the name: