From the WMAP site:
Originally Posted by EvilEye
By characterizing the detailed structure of the cosmic microwave background fluctuations, WMAP has accurately determined the basic cosmological parameters, including the Hubble constant, to better than 5%. This measurement is completely independent of traditional measurements using Cepheid variables and other techniques. The current results show the Hubble Constant to be 73.5 +/-3.2 (km/sec)/Mpc. If the WMAP data is combined with other cosmological data, the best estimate is 70.8 +/- 1.6 (km/sec)/Mpc. These results assume that the universe is spatially flat, which is consistent with all available data. However, if we relax this assumption, the uncertainty in the Hubble constant increases to +/-4 (km/sec)/Mpc, or slightly over 5%.
So the expansion rate is around 70 km/sec for every megaparsec (which is about 3.26 million lightyears).
So proportionately, if my arithmetic is accurate, the Hubble expansion rate over a distance of ~3 lightyears (which is still pretty far) is 0.00007 km/sec. (That's about 3 inches.)