SpaceX has successfully landed one of their first stage rocket boosters after putting a payload in orbit. This has never been done before.
For all space launches in history (except for this one), the first stage is jettisoned and destroyed during reentry.
The reason space exploration is so expensive for individuals corporations and even governments is the cost of launching mass into orbit. This is due in part to the expense of having to build and throw away the first stage for every launch.
A good analogy:
Imagine if commercial airlines had to throw away their Boeing 747s after every international flight. If this were the case, each trip would be so prohibitively expensive that no one except the richest people would be able to pay for it.
The Falcon 9 is the first rocket engineered from the ground up with reuse in mind. Hopefully we see many more Falcon 9 boosters recovered next year. If so, we could see the cost of launching something into orbit fall by as much as 80% by some highly optimistic estimations. This could mark the beginning of a new space age.