I use Outlook PCS. Works great. You can get it from here, Download details: Outlook 2002 Add-in: Pocket Contact Synchronizer 1.2
You simply install this, then go to the public folder you want synced, right click on it and choose to add it to Outlook PCS. Then you click on the button for PCS in outlook and it copy's the contents to your contact list. It also adds Outlook PCS as a category for those contacts so you can filter by them if you want. Then anytime you want to make sure you have the latest contacst from the public folder, you simply click the button. Wireless sync will take care of the rest.
I use this for my departments contact list. People come and go all the time. About once a week, I click on the PCS button in Outlook and I know within 30 minutes any changes will be reflected on my BB. I love it.