I just learned that the new macbook airs and macminis have bluetooth 4. (21-july-2011) with the iPhone 5 rumored to contain it. Assuming that includes the low-power mode, the sensor network is finally here. Oh wait this is Apple - they'll neuter it before shipping.

lowpower bluetooth4 is our best hope for spontaneous phone to phone discovery and messaging. (re: dating site)

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Dec 2012

Bluetooth 4le breakout boards

  Client only
  Chip: NRF8001
  https://github.com/nabilt/nRF8001-Breakout-Board
  Part: $2.50
  http://www.semiconductorstore.com/cart/pc/viewPrd.asp?idproduct=46669

  Master/client
  Chip: BLE112
  http://www.inmojo.com/store/jeff-rowberg/item/ble112-bluetooth-low-energy-breakout/
  Part: $18
  https://www.semiconductorstore.com/cart/pc/viewPrd.asp?idproduct=46652
  
  TI CC2540
  http://www.mouser.com/ProductDetail/Texas-Instruments/CC2540F256RHAT/?qs=sGAEpiMZZMsyM1rGGtQxrPlhStm%2fMGm9

  TurnKey
  $50 out of stock, new version arrives Jan 2013
  http://www.inmojo.com/store/jeff-rowberg/item/ble112-bluetooth-low-energy-breakout/
  
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March 2013

NRF51822 $2.50
http://www.semiconductorstore.com/cart/pc/viewPrd.asp?idproduct=47970

With extra stuff? $13
http://www.rfdigital.com/?targetpage=item&filterpn=51822

breakout board
?

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April 2016

smart bluetooth / BLE
TI CC2640

ATMEL ATBTLC1000
http://www.atmel.com/devices/ATBTLC1000.aspx