That's great news—SF has been the least affordable city in the country for a couple years: http://www.citylab.com/housing/2013/10/san-francisco-exodus/... , and for years I've been reading articles from people who say they a) hate high housing costs but b) also hate any new buildings. Which is amazing, because it's like saying, "I hate that supply and demand function!"
The solution to rising prices in the face of rising demand and constant supply is simple: build more, per Yglesias in The Rent is Too Damn High (http://www.amazon.com/dp/B0078XGJXO). That Lee is now doing so, on at least some level, is great!
As well, this boom and bust cycle (previous dcom era) fueled by outsiders makes it hard to live here for people who wish to make it their long-term or permanent home. The influx, transitions and seeming carelessness for our city & it's people can be very hard on families who have lived here for generations. This is why articles like this are written for multiple generations, as seen by some of the replies to the OP.
And that's just SF Planning. Numerous other SF Gov created problems also make development incredibly slow and costly. I'll just quickly list a few examples: SF Bulding Code does not permit plastic drain pipe; anyone can easily demand a hearing on an already issued building permit; SF Water charges $9000 for a new water meter; and rent control laws are strict and constantly changing. All of these are as strict or stricter in SF than almost anywhere in the US.
The reason for the jump in building is that office and apartment rents have become so ridiculously high it now makes sense to build in the few remaining sites despite all the costs. Even these projects had to go through tortuous approval process, such as the Transbay Transit District, and unbelievably many projects started back in the last tech boom! The building boom will likely grind to a halt in a few years as builders run out of sites.
Rant over. SF is a great place but this is in spite of it's crappy local government that has literally created many of its problems.