Bluetooth 4.0LE shares PHY features between "legacy" Bluetooth - 2.4GHz Frequency Hopping + GFSK modulation, but similarity ends here. Different packet format, different master-slave model, different security model are used for BT4.0LE. You have to have so-called "Dual Mode" capable chip on your host device (PC, SmartPhone, Tablet) in order to communicate with "Single Mode" BT4.0LE device (RF tags, health devices, keychains, etc).
Now, it is familiar "Chicken or Egg first" discussion. Will handset vendors implement BT4.0LE even though there is virtually no BT4.0LE device on market? Will device vendors produce BT4.0LE device even though there are very few BT4.0 capable host on market?
Someday sometime, it will reach to the "breaking point" and we'll see billions of BT4.0LE devices are rushing to the market, but it is difficult when it happens - or will it happen at all.