The open sourcing of .NET is the real news and as far as I'm concerned, the jury is still out on what that actually means for the world. Don't know about you, but I'll be sticking with JVM langs until I see a CLR for OSX on MS's download page.
Another thing that Nadella is doing is pushing new technologies and ideas which is not usually seen from MS. As the article mentions, MS was usually playing catch up or me too. These are promising changes, but still, because MS has been a fierce competitor who pretty much screwed over a lot of their partners and other companies that they've done business with, they became one of the most feared companies in the tech field. I'm left with the sense of waiting for the other shoe to drop. Maybe one of the reasons for that is the way MS pushed Windows 8 and their tablets. I've seen the corporate speak and boosterism that their people have been spouting when it first came out. Although it was still under Ballmer's reign, they are recent enough to make me wonder how quickly MS people can change under Nadella. Or if they'll even change. Nadella needs to make a huge impression to both the public as well as to MS employees if he's going to really change the culture and business practices of MS. In summary, Nadella seems to be the best person to do this job.