I unfortunately have no idea what picked/pickled data is och means, nor what cPickle module is, so I can't really help you there =/ (You're welcome to explain it though ^^)

I just looked into it, and you're quite right, it is indeed possible! While the fact that Anki utilises more than two fields to a card turned out to be no problem (it exports both fields on the backside of the card so that when Mnemosyne imports it, all backside data is shown in a single field), the most serious thing that was lost was all the scheduling data; i.e. all cards are imported as if they were brand new and have never been reviewed. This means that for us avid Anki users it's pretty much pointless to import it since it's the scheduling data that's the important part. Rereviewing 2000+ cards from scratch is not something that's done in the wink of an eye, and I personally would never do it if I didn't absolutely have to.

In other words, we have a way of importing decks from Anki to Mnemosyne, but if this is going to be of any use to Anki users that want to use Mnemosyne on the N900, then we still need to solve the issue of exporting/importing the scheduling data.

Edit:
Also, Mnemosyne seems to lack the feature of displaying furigana, which Anki does very nicely. A minor aesthetical drawback which just further convinces me that Anki is the better piece of software among the two of them ^^ The best solution would still probably be to just get Anki functioning properly on the N900 (Although digging around in the possibilities of exporting/importing files inbetween the two of them is quite interesting.)