Hi Arik -
Unfortunately there is not a mechanism for POSTing an array of keys in the .NET client. If you would like you can make a feature request here: http://www.couchbase.com/issues/browse/NCBC
It likely won’t make it into the 1.X version of the .NET client, but depending upon priority WRT other features, it may be in one of the 2.X releases.
-Jeff