Reading many forums, blogs, emails etc... about this law I kinda think lawyers are going to have a field day with it if police try to enforce. Some post were breaking down the laws into road/highway etc... The law was meant to gives us more room on the road, period!! Is this law enforceable, I agree with NR as I think not. We might need to ride with video cameras to adequately enforce it.
@ GB: Haven't noticed yet any improvement. I will have more info in the coming weeks. My most difficult road is Springfield with quite a few blind rises and curves. I get passed on these at an uncomfortable distance at times. I always get passed on these when the driver is at great risk in the other lane. One of these just happened on Monday. He had to return (sooner than I wanted) back into my lane. One of these days something is going to happen with oncoming traffic and the passing drivers. I gotta say I usually get respect from most drivers who give me way more than 3 feet.
Side note: there is very little education in MD drivers ed courses towards cyclist. I wonder if this law will be explained to the students. It should be as well as basic ways of dealing with us on the road.

Philly bike expo: looks great, you going to ride there:-)