I would treat this like a desert wine. You're not going to drink the whole bottle, but a small glass at the end of dinner is nice. You could do the same on an e-commerce site - work through the checkout process normally, and then make "Confirm purchase" button more fun to click.
Might be better to just animate them on click. Hover animations/color changes had some use for links, but a button shape already conveys "clickability". On the other hand, animating on click gives a nice feedback (how many times have I clicked a slow-responding link and wondered if I really did).
yeah, i kinda thought that same thing. these would be good to use for certain projects and in certain situations, but i don't think i would replace static icons with animated, ever.
overall, I feel that making every little button wiggle when I mouse over it would be distracting rather than helpful. I can't see myself using these.