'critical' is fine (or 'immediate'). My problem before was that I couldn't do one query that gave me all the critical issues for both 2.6 and 3.0. That certainly could have been pebkac though. Neal mentioned that that kind of query should be possible, if it's not already there.
I just created a "Showstoppers" public query (go to Your Queries/*edit*, and set it to "leave in"). This *just* searches for critical open issues, all versions. Given that there are currently really no critical issues, that semantically is the same as further restricting it to 2.6 and 3.0. Creating a query that searches for multiple versions is possible through URL editing, but not the form (currently). I'm not sure whether that would search for issues which are marked both 2.6 and 3.0, or for issues that are either marked 2.6 *or* 3.0. Regards, Martin