Importing dates like date of birth dosen't work with User import module. There is a clever patch with UI options for setting it up under user import configuration that can be found here but for users that want that patched already applied we provide it down below for download. It is current stable 6.2 version of module that is patched, with also additions of this two http://www.drupaldump.com/user-import-delimiter and http://www.drupaldump.com/user-imports-and-duplicat-emails customizations. One not is that your dates need to be in dd/mm/yyyy format in your CSV or some variation of it but "/" must be used for separation. Phpmyamdin will probably export your dates as mm.dd.yyyy which is not good for this module, how to fix this? You can't with latest excel as it transfers "/" into dots so you need to use some other program like easy csv editor and do this there. Even if you have dates like mm/dd/yyyy/ noticed the last slash it will still work.
p.s.
Tried to edit CSV with google spreadsheet, don't do it is just not possible to make it work for UTF