There’s a wonderfully careful analysis of various CC issues at burningbird. Thank you. One point to clarify, however. CC licenses are, at this moment, at least, permanent, in the sense that the term is as long as copyright runs (and we’ll see whether that’s permanent or not soon enough). That issue was a tough one for us (I, of course, favor “limited terms”), and we’re eager for feedback on that issue.
But just because you can’t revoke a particular license doesn’t mean you can’t revoke the offer. If, for example, you offer content under a CC license for a month, and then change your mind, you can stop offering the content under that license. Anyone who accepted your offer while it was valid, of course, has a deal. But no one after you withdraw the offer can accept anymore.
Finally, my blog is licensed in the xml. Button coming soon.