The sms-watch-python program makes use of the 'libmm-glib' library through
GObject Introspection to talk to ModemManager.

The program will:
 * Detect whether ModemManager is found in the bus
 * List all existing SMS messages stored in the modem
 * Print details of all new SMS messages (either from the network or the host)

The output will look like this:

$ ./sms-watch-python
[ModemWatcher] /org/freedesktop/ModemManager1/Modem/21: modem managed by ModemManager [862342010150533]: QUALCOMM INCORPORATED (0)
[ModemWatcher] /org/freedesktop/ModemManager1/Modem/22: modem state updated: disabled -> enabling (user-requested)
[SmsWatcher] PATH:                /org/freedesktop/ModemManager1/SMS/57
[SmsWatcher] NUMBER:              78273
[SmsWatcher] TEXT:                'Lieber Tchibo mobil Kunde, herzlich Willkommen in den USA. Sie k nnen hier wie gewohnt Ihre Mailbox einfach und bequem unter 333 erreichen.'
[SmsWatcher] PDU-TYPE:            deliver
[SmsWatcher] STATE:               received
[SmsWatcher] STORAGE:             me
[SmsWatcher] SMSC:                +491760000443
[SmsWatcher] TIMESTAMP:           2014-05-07T04:35:19+02

Note that the program requires ModemManager and libmm-glib to be installed in
the system and the introspection typelibs available in the standard paths.

Have fun!