I first heard about Bluetooth in 1999 (before I heard about wifi!). It was the most amazing sounding thing. All devices being able to easily communicate with each other, facilitating the Internet of Things. Its 2011 and Bluetooth is used for headsets, keyboards, and mice.
Battery drain and security bugs were two big detrements to Bluetooth adoption during its early years. The most important use case in my opinion, the ability to pass application-level messages between phones that have never met before, is sill not possible. For two bluetooth devices to communicate, they must "pair" which needs user intervention to complete. To even begin paring they must be discoverable. Being discoverable sends usage of the Bluetooth radio way up and becomes a noticeable battery drain. In the very earliest implementation of bluetooth, bluesnarfing was possible, where a phone's address book or other information could be copied without the phones having met before and without user intervention. This created a stigma that has remained with bluetooth discovery to this day.
With the relative popularity of zigbee - a sensor-network style protocol with neighbor discovery, low data rates, and extremely low battery usage - port of Bluetooth 4.0 is returning to its roots as a general purpose low power data transport. Its called Bluetooth low energy and chipset manufacturers are already selling wifi+bluetooth 4.0 chips that are ready for adoption into smartphones.
The smartphone automatic shared-interest app will get its best shot yet, very soon. Define what you're interested in, business, dating, buying or selling goods. When you get near someone who is running the same app on a bluetooth 4 smartphone, it could swap contact info for a later hookup, or start beeping loudly to say "hey someone in this room is selling that DVD you've been looking for. Here is their photo."
With IPv6 deployment finally starting to begin, the old set of 4 billion IPv4 addresses is being replaced with the new set of 340 trillion trillion trillion IPv6 addresses. The "limited" IPv4 address space was the driving force behind NAT which keeps individual devices from communicating directly. With the wide array of security holes in Microsoft Windows that existing during the first 10 years or so of the Internet's life and growth, the walled-garden effect of NAT was seen as a benefit, a critical measure of protection from viruses.
What was lost was a fundamental utility of the Internet, that devices should be free to communicate directly with each other. Instead of NAT, the entry points to corporate networks can use packet inspection to filter out unwanted traffic, providing the same safety benefit as NAT but allowing for the possibility of point to point communications that is important for new services, and new efficiencies for existing services to arise on the Internet.
If mobile operators adopt IPv6 addressing for mobile devices, it is one step towards a new class of smartphone apps - M2M or Mobile to Mobile. Voice and Video calls could be more efficient if traffic could pass directly between phones.
The Global Positioning System, deployed in the 90s, is slowly getting a host of upgrades that improve the ability to acquire a signal, the accuracy of position information, and resistance to interference.
What to watch for? GPS receiver chips that can listen to the new L5 signal from the Block IIF-1 Satellite launched in May 2010.