getResources tvFilter question (date filtering)

This is probably more of an SQL syntax question.

I have a TV called "mtg_end_date" that takes the date input format. In the database it looks like this:

2011-11-07 22:11:00

I want to use getResources to find a collection of resources that includes the following:
'mtg_end_date' values in the future (beyond right now)
'mtg_end_date' values that are null

How would I write that? The part I'm most unsure of is how to do "greater-than" math using dates. Is that even possible when the date is in this format?