The Census Bureau notes that telecommuting is on the rise:
Nearly 4.2 million people worked at home in 2000, according to Census 2000 tabulations, up from 3.4 million in 1990, the Census Bureau reported today. This 23 percent increase in home-based workers age 16 and older was double the growth in the overall work force during the decade.
Also these figures likely understate the number of telecommuters since they only count those who usually telecommute. So adding all those occasional telecommuters would boost the figure higher.
Telecommuters of all sorts will likely play an increased role in reducing traffic congestion, after all technology that enables telecommuting is getting better all the time. Even those who telecommute for only part of the day could have a big impact, since gridlock is such a time-specific problem. More people working from home during peak travel hours means less gridlock.