On 18/11/2011, Pontus Lurcock
Degrees, minutes and seconds of arc (also degrees Celsius) are an exception and are not supposed to have any space between the digits and the degree symbol [1], so to be correct, I think Context should by default veto any space between digits and numbers, in these cases only.
Correction, I should have written "(but not degrees Celsius)", apologies.
Conventions for setting the degrees of temperature symbol vary; see http://en.wikipedia.org/wiki/Degree_symbol#Typography and references therein. In most professionally published works that I've seen, there is no space between the number and the °, or between the ° and the C.
Pont, I agree they vary, and no space before the °C is quite common (and frequently my own practice too). However in setting default behaviour for Context I am inclined to favour conforming to international standards, where they exist (but a \setupunits override it probably called for). Robin