A key thing that is left out (But what most people have surmised):
Pacemaker <--MICS Band--> Home monitoring unit (developed by pacemaker company; obtains IP address - typically via dial-up.) <--TCP/IP--> PaceMaker Companies Servers <-- TCP/IP--> Physician Web connection
The 400mhz is considered to be the MICS band - http://en.wikipedia.org/wiki/Medical_Implant_Communication_Service . The great thing about MICS is that it covers not only 'both sides' of the pond, but pretty much all sides. (E.g. Asia, Europe, and the US). The 'challenge' with 400mhz is that it's only a 'few meters' coverage. So you have to have the home monitoring unit (the unit that actually does 'connect' to the internet and the implanted device) within a 'few meters' of the device/patient.
Pacemakers are very small, compared with an ICD (defibrillator). In both cases, battery space is one of the biggest uses of the volume of the CAN. (in a defib you also have a large capacitor). The more energy you use for communication, the faster you drain the battery - and the less power you have for therapy. No one has an 'externally rechargeable' unit - so the only option is to put the patient under for surgery and replace the unit. (Low risk - BUT, there is a risk... and it's a surgery. and these things aren't cheap)
It will probably be a long time before your pacemaker signs on automatically to the local WiFi connection to 'dial home' to the physician. (Power, security, and proprietary data communication formats to name a few reasons).
One commenter early said, "pacemakers have been connected for years" - that's via "TTM" - http://www.google.com/search?q=transtelephonic+monitoring+pacemaker&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
TTM doesn't provide very much data from the CAN. Basically and EGRAM, battery strength, and maybe a few other items. The at home monitoring unit can pull more data from the can.
The great thing about these systems are the peace of mind from monitoring the pacemaker on a daily/weekly/monthly basis versus once every 6-12 months or 'when the patient feels bad.' And when the patient does 'feel bad' the physician can pull up the latest information from the pacemaker the help determine if the patient should come in or not.
St. Jude (Featured) - House Call - http://www.sjm.com/devices/device.aspx?name=housecall+plus+remote+patient+monitoring+system&location=us&type=10
Boston Scientific - http://www.aboutlatitude.com/
Medtronic - http://www.medtronic.com/physician/carelink/index.html