The first time I drove in California and had a pack of harleys split by me on the freeway (I was in traffic doing 10-15, they were easily doing 50-60mph) it scared the shit out of me.

They definitely got where they were gong a lot quicker than the cars sitting gridlocked.

Splitting would ease conjestion, but in our climate it would only have a great impact during the warmer months when more people ride. I don't see a problem with passing laws allowing it though, it really can't hurt anything IMO.