SpaceX is no longer limited to reusing rockets -- it's reusing capsules, too. The private spaceflight outfit has launched a refurbished Dragon cargo capsule (namely, one last used in September 2014) as part of a resupply mission to the International Space Station. While the vehicle isn't as complex as a Falcon 9, this shows that it can endure multiple launches (SpaceX is targeting three) without a hitch. That's important for reducing the overall costs of spaceflight, especially when manned Dragon missions become a reality.
The team also successfully landed the Falcon 9's first stage at Cape Canaveral, although these touchdowns are becoming nearly routine at this point. SpaceX wants to land as many rockets as possible going forward, but it's limited until Falcon Heavy arrives and it can routinely expect to have enough fuel for return trips.