It seems that the sensor can rotate.
Direct infos from Pentax : http://www.pentax.jp/english/news/2011/201107.html
You may go up to 5 mn under 50 mm or at 200 mm in good conditions. Amazing.
Looking at the picture, one is 60 s à f=100 mm, an other one is 75 s f=43 mm. Quite impressive.
IMHO the tester is not aware of astrophotography, indeed the results are already good. With my Olympus E-510, I accumulate shorter views (60 s) with smaller focal length (50 mm) using an home made equatorial mount.