The first MetaPLoP will be held in Portugal immediately following the Agile PT conference. The conference will be preparing a collection of the best "meta" patterns out there today for publication in a forthcoming TPLoP edition.
The second AsianPLoP has been rescheduled for October 5-7, 2011 in Tokyo, Japan. Joe will be attending as will other pattern enthusiasts.
Metadata is just saying that if something is going to vary in a predictable way, store the description of the variation in a database so that it is easy to change. In other words, if something is going to change a lot, make it easy to change.