BlackBerryContactList list = (BlackBerryContactList) PIM.getInstance().openPIMList(PIM.CONTACT_LIST, PIM.READ_ONLY);
PIMItem contact = list.choose();
This lets you navigate, edit, and choose a contact. After that you can use the chosen contact's information to call, or sms, etc.
If the native selector isn't what you want, iterate over the entries in list and build your own.