Some users on the PSN forums has reported that the last update bricks the 32GB memory cards.
After the update, the device won't start with the memory card inserted.�
http://community.us.playstation.com/t5/PlayStation-Vita-Support/Update-3-10-Bricked-My-PS-VITA/m-p/43214930
http://www.gamefaqs.com/boards/620272-playstation-vita/68877226?page=9
So far for now, 16,8 and 4 GB memory cards seems to work fine.