getCenterLatLng() and getZoomLevel()

So, I've been looking around the discussion group and I'm not sure I
understand how to use (or if I can use) the getCenterLatLng() and
getZoomLevel(). I haven't understood how others have used these either
from what I'm seeing.

What I want to be able to do is allow the user to drag my map all
around, zoom in and out, and then mark my map. As they submit a mark
onto my map, I want to refresh the map div (to refresh with their
point), but I want to preserve their last center lat and long and zoom
level. I'm thinking I need to capture their last map center postion
and zoom level in a variable.

So, I don't know exactly how or when to use the above (or if they will
even work as I described) to return the info I need. Can anyone
explain how they or others are accomplishing this? Thanks in advance.
beckwiga.