Amidst yesterday's ebullient selection of Satya Nadella as Microsoft's new CEO was a question the firm wasn't willing to discuss: Who would succeed Mr. Nadella as chief of the firm's Cloud and Enterprise group? We now know that star engineer Scott Guthrie—"Scott Gu" to insiders, and infamous for his red shirts—has been promoted. But an important question remains.

News of Mr. Guthrie's promotion comes courtesy of my Windows Weekly cohost Mary Jo Foley, who doggedly pursued this story while everyone in Redmond was celebrating Nadella's ascension to the top spot at the company. But as she notes, Guthrie is not—yet, anyway—the permanent chief of this important division. Instead, he's the "acting," or "interim," Cloud and Enterprise Executive Vice President at Microsoft. He will report directly to Mr. Nadella.

But why "interim"?

Foley told me that the interim title is just a formality and that Guthrie's full-time promotion to the head of the group is all but assured. His new role was announced internally on February 4 but has yet to be acknowledged publicly beyond Foley's report. Guthrie doesn't appear on Microsoft's Senior Leaders page, nor does the Cloud and Enterprise group, at least for now.

For those who don't know him, Mr. Guthrie is a plain-spoken advocate for Microsoft's developer and cloud platforms, and he most recently ran program management for the firm's Windows Azure business. Guthrie is a frequent and popular speaker at Microsoft events—where he's known for wearing those red shirts—and a blogger.

Actually, this does raise another question: If Scott Guthrie is going to take over Cloud and Enterprise, who is going to run Windows Azure program management?

Related: Get an early-bird discount on our upcoming Windows Azure for IT Professionals training