Here's an interesting measure of the depth of the economic recovery in Silicon Valley: Traffic has gone from bad to unbearable, according to this piece in the San Jose Mercury News.A survey of Silicon Valley CEOs shows that traffic concerns have risen from ninth in 2005 to second this year among their top business challenges. (No. 1? Easy. Housing prices.)Moral to the story: Stewing in traffic beats not having a job, but that's hard to remember when you're stewing in traffic.