1. elabel has not (to my knowledge) been ported to v3
2. the InfoBox in v3 can be used to create labels
3. I'm not sure how complex your kml is, but if "a number of
placemarks" is small enough you could look at using geoxml3 to display
your kml (KmlLayer won't give you access to the markers), and create
code that would put labels on the Placemarks. You could also add a
"title" to the markers that could display a tooltip rather than a
label.
Example putting labels on a map with kml on it (but not using the kml
to place the labels):
http://www.geocodezip.com/ParkerPalmSprings.html
-- Larry