Via Tommaso Dorigo of the CDF collaboration, the news that the Tevatron Electroweak Working Group has released a new analysis of combined CDF and D0 data with the most accurate result so far for the top quark mass: 172.5 +/- 2.3 Gev. Last summer this value was at 174.3 +/- 3.4 Gev (see a posting here), an improvement over the earlier value derived just using Run I data of 178.0 +/- 4.3 Gev.
The paper describing these results is available now here, and will soon be on the arXiv as hep-ex/0603039. This new result represents a determination of the top quark mass to 1.3% accuracy, and the paper claims that further Run II data should ultimately allow an accuracy of better than 1%.
For a talk about the significance of the top quark mass, see here.