For Firefox 3.6 and later we should include information about plugins which we know have updates available for in the blocklist xml. These should be included in the same way as a standard plugin with the regexps just with a severity=0 (pending bug 514327). We may want to rev the schema number in the blocklist URL so the service knows to include this I assume?

What do you need -- a URL stored with each plugin blocklist entry? How is this separate from the plugin update efforts? Why tie it to the blocklist?

No url, just a normal plugin blocklist entry with severity="0" will indicate to the client that an update is available but that the plugin does not need to be completely disabled. The user will then be pushed towards plugin update page.

This already works in the service, then.