Directories getting zeroed out all over the place

Which ones get canned, and which don't?

[ownerrim]

I've been looking at lists of directories the last few days. Most seem to have pagerank and some have an appreciable amount of pagerank. But a noteworthy number are now "greenless" ie no pagerank. Bluefind seems to be the most notable, I suppose, but lots of others no longer have pagerank.

Why are some keeping their pr and why are others getting the knife? Are there lessons here for future directory builders?

[webmasterguy]

Wish i knew!

[Event_King]

Small directories have ever changing content. Some have none and some have a little content - some webmasters just don't know what content to have, and maybe they chop and change so much that Google probably is unsure about what Pagerank to give them.

Or maybe PageRank is screwed. Something's up with it -that's all I know. Mine keeps appearing then disappearing. I suppose the next update will sort things out.