I run a PR 4 site. Recently, a couple of pages have been appearing with PR 1 and PR 0. I read on another site that PR0 is a penalty, but these are well written informative pages and importantly, pages that appear as 4th or 5th results when their titles are searched for. They are very popular pages, and pages that are edited often. Essentially - is PR 0 bad or good or what?! Thanks!
PR0 is not a penalty. Its just the start of the ladder towards PR10. PR got nothing to do with SERPs as you already noticed.
PR0 normally means it is a new webpage, but doesn't have any implication whether it is a good page or not.
No, it's not a penalty. PR is not directly related to serps. Suppose you tell a story about the flees on your dog in your blog post. The PR of the post could be 0 as your story about your dog's flees probably has no use to anyone. Yet when someone searches "dog flee story", your article may show up because it is relevant to the query.