It was a real shame that javax.units (aka JSR-108) died because of lack of interest. Some nice libraries already use it (geotools for example) and the Java world doesn't have a standard way of talking about units.
Unit measuring seems a very handy way to prototype some nasty formulas. Remember the old: forgot it was metric unit error ?
Well, now javax.units is reborn under JSR-275, with a RI based on JScience. There also seems to be a new package now: javax.quantities. I'm going to read the spec to see what's this about.