See the Metafilter link for some great comments. Time travel makes my head hurt, but I love it anyway.
I foresee two possibilities. One: coming face-to-face with herself 30 years older would put her into shock, and she'd simply pass out. Or, two: the encounter could create a time paradox, the result of which could cause a chain reaction that would unravel the very fabric of the space-time continuum and destroy the entire universe! Granted that's a worst case scenario. The destruction might in fact be very localized, limited to merely our own galaxy.
-- The Doc