I was very suprised that the default measure for Inkscape is pixels, as these are typical measures for bitmap images, and not for vector graphics.

And, btw, what does a fraction of a pixel mean?

We use it because its the unit thats used as the default in the SVG spec.
see:
http://www.w3.org/TR/2003/REC-SVG11-200 ... html#Units

Even though the units can be easily changed to something else, I rather prefer Inkscape to be in pixels. That way when I work in both Gimp and Inkscape I don't have to change or convert units.

I like pixels because in most cases my work is displayed on a monitor and monitors are measured in pixels. I dare say that's why the standard uses pixels by default also, as SVG is format for viewing in a browser--it's not a print format (yet).

I think the important thing to remember that whilst it's measure in pixels, it is still vector and you can still have fractions. And pixels are not a physical unit so when it comes to printing you can choose how big a pixel is. For example if you draw a circle that has a 4 pixel diameter, you can decide that each pixel will be 1 inch when you print it and you'll get a perfect 4 inch circle on the page.

Horses for courses. When I use Inkscape to create icons, pixels is the only sane measurement.

It also begs the question, if pixels weren't the default measurement, what should it be? Americans would likely want inches, and Europeans millimeters.