I am showing a drop in PR from 2 to 1 for my site but with a dramatic increase in backlinks. Traffic is holding steady at 200+ uniques per day. I am pretty sure my website is in sandbox as it was a new domain a few months ago and we dont list in the serps for anything remotely competative. Not sure how google has changed the PR calculations but I think it may have simplified it. Perhaps PR will not count for much anymore.