NAD+ is just niacin
No, Niacin is a precursor to NAD+. It not clear that you will get significantly more NAD+ if you raise niacin levels.
If some enyzm on the way towards NAD+ doesn't get expressed enough having to much Niacin might mean that some precursor for NAD+ is to highly concentrated with kicks of reactions you don't want.
Niacin has a upper level recommendation for the FDA. This might be a reason to make sure that you don't have niacin insufficiency in your diet but I wouldn't take this study as evidence for taking higher a higher B3 dosis.
This seems like an advance in understanding, even if it doesn't lead directly to a treatment.
News stories:
http://www.theguardian.com/science/2013/dec/20/anti-ageing-human-trials?CMP=EMCNEWEML6619I2
http://www.bbc.co.uk/news/health-25445748
Abstract of the paper, actual paper behind a paywall:
http://www.cell.com/retrieve/pii/S0092867413015213?cc=y
Relatively solid stories like this help raise my estimate that significant life extension is possible in our lifetimes. The likelihood seems to be that it won't be a "magic pill" but a combination of therapies.
If nothing else, it's another reason to eat healthy and stay in shape.