I'm watching the 60 Minutes article on NYC's response to terrorism, police surges, for example.

The other day, I read an AP article saying that numbers of rental units were declining.  This Reuters article says much the same thing:
http://news.yahoo.com/s/nm/20060308/us_nm/property_apartments_study_dc

So, it is one thing to talk about moving close to work, but quite another to find someplace available.  

It'll only get more valuable over time. In talking to people about why they are willing to pay so much for such small spaces, the answers are easy: No car payments / insurance / gas / repairs. When I owned a car in Queens and used it just for weekend stuff, it easily cost about $3-4000/year and gas was a minor cost. The incentive to live in dense urban areas will only increase as gas prices rise.

The best thing that the city can do is start rezoning a lot of the major mass transportation hubs for increased density. Then start a cycle of expanding the reach of good mass transit to service more areas and then increasing their density...rinse and repeat. This was NYC's pre-Robert Moses defacto development strategy. After a 75 year auto-obsessed interlude, this is starting to happen again in some areas but will take a long time to realize fully. It would be a lot better investment in light of PO than trying to sustain the 'burbs.