The Library of Congress, backed by the far reaching powers of the Digital Millennium Copyright Act (DMCA) have basically ruled that if you have a phone on a plan (subsidized handset) that you don’t really own it – the carrier does and you cannot mess with their property. The great majority of phones in the US are sold in this manner. This will also apply to tablets that are purchased on a Telco plan.
The other consequence is for international travellers who want to use a local SIM when travelling. Carriers will have no obligation to unlock to allow you to do this.
And this is just the tip of the iceberg as it will now give manufacturers the excuse to embed a carriers SIM card onto the motherboard removing any opportunity to slip in a new one.
For those who are outraged let’s just say that the computer world is littered with instances where you don’t actually buy hardware or software but simply a right to use it according the EULA (end user licence agreement). In short the manufacturer can, in these circumstances dictate what you can and cannot do.
Summary: Telcos world-wide will latch onto this legislation and use it as an excuse to enforce compliance. The solution is simple – buy the handset and the rule does not apply although this could put upward pressure on prices.
PS - for the non-techie reader I have taken liberties using the term Jailbreak (which is a process to allow iPhones to run pirate software etc) to mean the same as unlocking from a carrier network.