MyMote is an awesome MythTV remote for the iPhone.
The best part about it is that the progam guide displays on the remote allowing you to quickly scroll through the program guide with the iPhone finger flick scrolling thing.
Before I got my iPhone I was using my N800 or a standard remote via LIRC as my MythTV remote, but MyMote is much better.
MyMote is available as a free install from the app store. So you don't even need to jailbreak the iPhone to get it .
Just search for "mymote" and install.