This would be reusing a significant part of its orbital rocket, a very productive type of rocket. Suborbital rockets have been reused since the 1940s, at least, with the Air Force’s X series of rocket powered test planes, a very informative type of rocket.

Either way, Rocket Lab and SpaceX are showing us that the impossible can be done. Hopefully, Blue Origin will get back on pace to once again show us other impossibilities that can be done. They were, after all, the first to land and not splash a booster for reuse.

The short amount of time, two and a half months, suggests to me that they have very few refurbishments to do to the rocket for reuse. This can make for a very inexpensive reusable rocket.

From the article:

All previously recovered boosters have undergone extensive analysis to inform an iterative development process to make Electron reusable, but this is the first time a tank has been moved back onto the standard production line in preparation for reflight.

It sounds as though this is only the basic structure (“fuselage”) but not the engines that are reused for this future flight. My recollection is that they were able to reuse one of their engines recovered from an even earlier flight.
https://behindtheblack.com/behind-the-black/points-of-information/rocket-lab-launches-a-satellite-reusing-one-rocket-engine-from-previous-flight/

If this stage successfully passes and is accepted for flight, we’ll consider opportunities for reflying it in the new year.

Sounds like next year.

Hooray for Rocket Lab, that their rocket has not suffered any obvious harm from the ocean water. If the qualification testing (re-qualification?) works out then they did good design work. If not, they will learn again where to do better, because they obviously are not too far off the mark.