I used the transfer data app which came with the Z and transferred my SMS via bluetooth. My address book and calendar was already synced with google using google sync on the BB. It worked fine until I restarted the phone and then it started to RESEND EVERY SMS it imported BACK to the person I was texting, one by one. I had to go into airplane mode and delete them all and someone else here had the same problem, so be careful.
if its just contact info, then use the google sync app on your bb.