Yes, the fact that America will be launching american astronauts from its own soil to re-crew the ISS for the first time in several years is a big deal, but how is a commercial mission different from, say, the Apollo missions, or the space shuttle program? Well, over the past few years NASA has made some major changes in the way it does business. From the beginning of its manned missions, NASA ran everything and did everything having to do with its missions. By the time the space shuttle program came along they didn't even use outside contractors the way they did with the Apollo program. NASA actually built and maintained entire fleet of shuttles itself. And contrary to the promises of vastly lower costs for access to space, the shuttles actually ended up being grossly more expensive than the disposable space systems they were replacing.
So, once the shuttle program was over, NASA decided to turn itself from something like a vertically integrated corporation into a facilitator: The new NASA would set goals, hold competitions between commercial contractors to fulfill those goals, and set and test an ongoing series of benchmarks for these contractors to fulfill before proceeding any further toward winning and keeping each contract. There have been two major improvements due to this new approach: first NASA is actually making access to space cheaper, really! Second, by cultivating multiple contractors, NASA has multiple options simultaneously. Imagine if, instead of building the shuttles themselves, NASA had its current facilitator role: Once NASA saw that costs were ballooning, and that, essentially the shuttle design was a dog, an expensive dog, NASA could have just cultivated another option.
As it stands right now, through its Commercial Crew Program, NASA is responsible for encouraging two platforms into being: Boeing's Crew Space Transportation system (the CST-100) and SpaceX's Dragon capsule. And if one or the other contractor starts going significantly over budget, or stops meeting the benchmarks NASA has set out for it, NASA can take a different path. So, as you can see, this is a much more nimble paradigm that NASA has taken on.
So far, Boeing has met all of its benchmarks, and passed all of NASA's qualifying tests for the CST 100. And so it has won NASA's first commercial contract to ferry astronauts to the ISS.
"This occasion will go in the books of Boeing's nearly 100 years of aerospace," says John Elbon, vice president and general manager of Boeing's Space Exploration division, "and more than 50 years of space flight history. We look forward to ushering in a new era in human space exploration." And if Boeing and SpaceX can continue to keep costs under control, it really will be a new era. Because once costs for space access are controllable and predicable, and with economies of scale, perhaps into a trend of truly becoming less and less expensive over time, so much more in space travel will become possible.
(Sources: phys.org, wikipedia, NASA, Boeing)