hm - managed to get it working, though i'm not really sure why. i reinstalled the power kernel, since from what gameboyrmh said it was likely not the problem, rebooted, then cleared the gps cache using the script from https://bugs.maemo.org/show_bug.cgi?id=7026#c35 and it suddenly started working again. the weird thing is, i've cleared the cache several times without it helping; no idea why it worked now.