[pronoiac]

Say the blockchain's growing by a gigabyte a month.[1] I don't think SMS can support that much, especially times so many devices. Using a tv signal is more robust - you can support millions of devices, and transient 3G network failures will have less or no effect.

[1] I estimated. http://blockchain.info/charts/blocks-size

[nawitus]

But the parking meter (etc.) doesn't need to handle the blockchain at all. It could use the SMS to communicate with a shared parking meter bitcoin transaction server. That said, broadcasting the blockchain is useful.

[zouppen]

If you stick to centralized solution then that would work nice and might be good enough. However Kryptoradio allows to do it by just listening incoming transactions and blocks.