Long-term-potentiation and memory. Where do we stand?
Is there clear evidence that LTP is involved in long-term memory (not
  counting 1 hour as long-term...)?  Has LTP/LTD been shown in vivo
  after long period of time (e.g. months).


This Journal of Neuroscience paper shows LTP in vivo measured out to one year:  Abraham WC, Logan B, Greenwood JM, Dragunow M. 2002. Induction and experience-dependent consolidation of stable long-term potentiation lasting months in the hippocampus. The Journal of neuroscience : the official journal of the Society for Neuroscience 22: 9626–34.