Can operators be used on the date variables? For example, is there a way to determine if the date of a post is after a specific date?

The data custom fields would still be in their unix timestamp form, so you would have to figure out the unix timestamp for your cut off time.  Otherwise, you would have to use PHP on Output so that you could do a PHP conditional with the date variable translated into a more human readable format.

Hm, perhaps the “Utilities section” in CP Home > System Administration could feature a “Convert from/to UNIX timestamp” tool in an upcoming version? Just a thought ...

(Yes, yes,  I’ll make the feature in the appropriate place.)

Excellent. Thanks for the info, Paul.