Ha!

A bit funky but it'll work - you have to find your Nike id which may be found in the web address when looking at all your runs on the Nike site.

If you make your profile public, Slowgeek will be able to pull your runs and you can get a CSV file of all your runs from there. You can see an example here: http://slowgeek.com/pr/rlerdorf

On the right above the table of runs you will see a little disk icon. Click on that to get a CSV file of my runs.
http://slowgeek.com/

If you use Sporttracks, there is a CSV file import plugin. Of course, you can alway add your 2 cents on the ST's forums asking for a NikePlus import plugin.