Things are looking up for 401(k) plan members. In large part it's because members helped themselves while the market turned to quicksand in 2008 and early this year. In plans run by Vanguard Group, the median account balance on Sept. 30 was actually up 7% from two years earlier. In September 2007 the market was close to its all-time high. "In other words, the typical 401(k) participant at Vanguard now has higher 401(k) retirement wealth than