I agree that Snowden's credibility is incredibly important here. However, the NSA's credibility (and transitively, the administration's) is also incredibly important since almost their entire defence boils down to "just trust us". Currently I haven't seen anything to suggest that Snowden is lying except that some of his claims are fairly outlandish and some are contradicted by what Google et al are saying - however they're fairly highly incentivised to at least fudge the truth a little under their current constraints. On the other hand it's pretty clear that Clapper lied under oath to a senator ("least untruthful"? Seriously?) so the onus is on them to recoup their credibility. I'm also anxiously awaiting more slides.
