Björn and others, I beg to differ!
This bird is a juvenile White-backed Woodpecker (WBW) that left its nest just 3-5 days before this picture was taken. I have followed this nest during this spring, and its mother can be viewed here: http://cyberbirding.uib.no/photo/d_leucotos_02.php
The bill of the WBW is not fully grown when they fledge. According to the BWP the bill is fully grown at the time when the post juvenile moult is complete, and that is in september. Other characteristics on this bird indicating WBW is better shown on another image that have posted here: http://cyberbirding.no/photo/dendrocopos_leucotos.php. Note the broad malar stripe, densely flank and breast streaking, and also the bill - it would be rather powerful for a Lesser Spotter Woodpecker I think. The size of the bird was like a WBW, and the call the same.
Anyway, when looking at the picture posted at netfugl I would assume it could be a nice candidate for a mystery bird competition :-)