I reverted to nokia kernel in maemo and uboot-pr13 and the wifi problem in MeeGo remains. So it is obviously (it was pretty obvious beforehand too that a different maemo kernel should not have any effect on MeeGo, but it was the only change before and after the problem, and the only serious difference with my other device that already had the wifi problem so I had to give it some thought) not kp nor uboot related problem. I will ask again on the MeeGo CE thread. Thank you anyway for all the efforts.

EDIT: Sorry guys for the false alarm. When I was thinking what extra info I should include on the bug report for the wifi issue, it struck me what the only thing that was the same on the two devices while having the problem. The sim card. I removed the sim-card, and voila! Wifi available. (Funny thing is that with an older sim of the same carrier wifi works fine)