Maya's got a funny way of showing that it loves you. Here are the steps you need to take to get it to behave correctly. You should only have to do this once. (Until you have to trash your pref's. Then you'll be doing it again.)
1. Set default frame rate and initial animation length. From the menu bar, choose File > New > Options Box. Set to NTSC 30 fps. You'd think this would be under preferences, and it is! It just doesn't act as a default there. Good lord.
2. Open a new file.
3. Set playback to Real Time (30 fps). Under Maya > Preferences > Settings > Timeline > Playback. Also, go ahead and set Looping to continuous.
4. Set Default in and out tangents to Linear. This is under Maya > Preferences > Settings > Animation. Go ahead and check the Weighted Tangents box here as well. Ha ha, notice there are two categories of "Animation" in the preferences panel. Make sure you're on the right one. Brilliant.