These experiments with transitioning variable font styles on hover might be silly, but I can see the potential for some beautiful interaction design.
An excellent little rant by Cennydd that I agree with 100%: hovering does not demonstrate user intent.
A timely reminder: don't hide information behind mouseover events.
Amazon is AB testing their next design iteration. Bye, bye tabs (yay!), hello fly-out menus (boo!).