GGJ is right (as always!), but there are a load of iPhone apps which let you use your iPhone as a trackpad and keyboard, and some of them have built in apple remote functionality as well.
If you want to be able to access many of iTunes' features (selecting songs, artists, albums, shuffle etc.) then try front row (press menu on your apple remote), although don't get used to it because, from what I understand, front row is AWOL in Lion.