I've found answers to my XAML menu throbbing questions! Using RoutedEvents in ControlTemplates (and DataTemplates!) lets me start and stop timelines for animations. I can place these triggers inside styles, and it turns out TargetName isn't always required. A cool discovery: storyboards inside ControlTemplates/DataTemplates can be accessed by any control matching the style's TargetType. My wobbly menu example demonstrates these techniques.
I had this cool idea to add some throbbing action to my GelButton menu items in XAML. I wanted them to subtly pulse when hovered over. Turns out, it's harder than I thought! I've learned some limitations in XAML (May CTP): you can't start/stop storyboards from triggers, apply a single animation to all controls of a type, and TargetID is deprecated in favor of TargetName. Points 1 & 2 are especially problematic as they blur the lines between UI and application logic. I'm going to look for workarounds and see if others have solutions. Might even post my (probably wrong) ideas on how things should work.