The PAM module pam_thinkfinger supports fingerprint authentication for the following applications and actions (although you may not be prompted to swipe your finger in all cases):
Logging in to GDM/KDM or a login shell
Unlocking your screen on the GNOME/KDE desktop
Starting YaST and the YaST modules
Starting an application with root permission: sudo or gnomesu
Changing to a different user identity with su or su - username