Earlier days I had in Nokia Communicator profile changing application that used network cell IDs for profile activation. That is basically ok, but you needed to find all cell IDs near your home/work (for both 2G and 3G networks). For this WLAN ID as mentioned could be more useful. Another application used calendar to set profiles. E.g. if you had a keyword "meeting" in your calendar the application changed proflie to silent/meeting for that time. This was pretty useful and it also had time based profile setting for handling work/home profiles.