In his open, "Dear Satya" letter, Ballmer betrays no obvious animosity, but does casually mention that major shareholder thing:

I bleed Microsoft -- have for 34 years and I always will. I continue to love discussing the company's future. I love trying new products and sending feedback. I love reading about what is going on at the company. Count on me to keep ideas and inputs flowing. The company will move to higher heights. I will be proud, and I will benefit through my share ownership. I promise to support and encourage boldness by management in my role as a shareholder in any way I can.

Nadella politely acknowledges the power Ballmer still has to wield, while reminding his predecessor he has plenty to keep himself occupied:

As you embark on your new journey, I am sure that you will bring the same boldness, passion and impact to your new endeavors that you brought to Microsoft, and we wish you incredible success. I also look forward to partnering with you as a shareholder.

I wonder if Steve Ballmer and Bill Gates are willing to let Microsoft do things they don't believe in.

It's pretty odd for founders to walk away.

Steve Jobs kept his job till the day he died.

Looks like Larry Ellison and Warren Buffett plan on doing that, too.

That first sentence - what are you really saying?

They might be preoccupied with the Gates Foundation and the Clippers but they can still place a phone call and prevent Microsoft from doing things. 

Oh, I thought you might be referring to something specific Satya is doing.

Not yet. Though I can't say anything he's doing gives me confidence in the future of Microsoft.

They're just lucky people are so reluctant to leave Microsoft Office.