As BlackBerry users, most of us either have devices that are unlocked right now or have unlocked a device in the past. A move that starting January 26th will be considered illegal. In case you're not sure what unlocking means, it's in essence just the ability to "free" your phone from your current network. You can then pop in another network's SIM card and use your phone on that carrier without a problem (There are, of course, limits of which network your phone can run on when unlocked depending on compatibility between the hardware and carrier).
The Digital Millennium Copyright Act, a law originally created to hamper hackers and goes into effect on Saturday, basically makes it illegal for the end user to go out, pay someone to get a code and unlock their device with it.
One thing that must be pointed out is the fact that this new law will not affect cell phones that were purchased before the January 26th deadline. Let's say you have a Bold 9900 that you bought 6 months ago, even after January 26th, you will still be able to legally unlock it with no problems.
Also, this law does not prohibit the end user from asking the carrier that sold them the device to unlock it. If AT&T or any other carrier, for example, is willing to help you out with unlocking your device that was purchased after January 26th, then it would be completely and totally legal.
With this law going into effect 4 days before the launch of BlackBerry 10, one has to wonder how this will affect the devices that RIM gives away from this point on.