[Zope] Matching a date that's in a Zcatalog field index

I've set a CreateDate property on a bunch of files--basically, i grab the ZopeTime at the time of the DTML Document's creation and write it to a CreateDate property of type date. Now I'm trying to pull individual dates out of the Catalog--for instance, to show all of the stories written today. What's the proper syntax for matching this stuff? This doesn't work: <dtml-in "NewsCatalog(CreateDate.Date()=_.ZopeTime().Date())"> </dtml-in> Thanks! - Chris