Comment 22 for bug 168164

As was stated above by Tom Davidson, there's a couple of ways to convert between inkscape pixels and points. And both are tedious :-p
You can manually change the size of every type object using the XML editor, or use a factor of 1.25 to convert the desired point size into pixels.

Inkscape uses a resolution of 90dpi for the "real-size" representation. So, if you create a 90x90px square it will be 1x1 inches in "real" units.
A typographic point is 1/72 of an inch, which is equal to a resolution of 72 dpi.
90/72=1.25. So 1.25 is the factor you can use to translate between inkscape pixels and real-world typographic points.

I guess it would be pretty trivial (and probably a horrible hack) to add a unit selector in the text dialog to choose between points and pixels using just that factor. Internally it would simply multiply or divide the desired size by 1.25.
It doesn't sound like an elegant solution to solve the problem, even for my non-programmer brain. But at least it would be a temporary fix for an old bug that people who work in print production have been asking for years.
IMHO, after four years since the original report and millions of multiplications and divisions by 1.25, even the cheapest solution looks good :-)