Constraining the expansion rate of the Universe using low-redshift ellipticals as cosmic chronometers arXiv:1010.0831v1

Authors used a spectral feature around 4000A of Early Type Galaxies (ETG) to measure the Hubble constant. The result, H_0 = 72.3 \pm 2.8 (68% confidence), is in a good agreement to that of WMAP, and the error (systematic dominated?) is comparable to the one from SNIa.
Since the method is a direct measurement of the age of galaxies, it will be very useful for cross checking the values of w(z) etc... measured from other types of future DE missions.