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Yes, SEOmoz did change the way they calculate DA and PA. That blog post (and the other referenced in it) give a lot of the background information that'll help explain things for you. For this update and future updates, I'm going to have a Q&A discussion question that also alerts people to these types of changes, as I know not everyone has a chance to read the blog for those notices.

Linkscape, which powers Open Site Explorer, only crawls the top 25% or so of the web right now. Also, the crawl is done once a month, so that's why it can take some time to show up. We're working on getting the crawls faster, but that is why things are slower than Google. We have a few less servers than they do at our disposal to make the crawls. We did just have an update this morning, you might want to check out the blog post from Rand for more information. http://www.seomoz.org/blog/2nd-november-index-update-our-broadest-index-yet-and-new-pada-scores-are-live