Apple's market capitalization of $227.1 billion, based on its stock price on the afternoon of May 26, made it the most valuable U.S. technology company--edging out Microsoft and its $226.3 billion market capitalization. In Cupertino, I'm betting some Apple executive has popped a champagne cork, or at least begun blending a celebratory organic smoothie.

Those numbers managed to place Apple second on the list of highest-valued American companies, behind Exxon Mobile and its $282 billion market cap. It also represents a marked change from August 2008, when Apple's market cap exceeded Google's for the first time, but lagged far behind Microsoft's at $254.83 billion.

(Before anyone gets too hot and bothered over those figures, let's remember that Spain could announce tomorrow that it has exactly $1.24 left to its name, and through the miracle of globalization send the markets into a tailspin that alters all those numbers completely.)

Rob Enderle, principal analyst of the Enderle Group, wrote me in an e-mail this morning that Apple's market-cap eclipsing of Microsoft may have been one of the factors in Redmond's decision to revamp its Entertainment & Devices Division, of which the various products--including Windows Mobile and the Zune HD--have lately not performed as hoped (the Xbox franchise is an exception, having turned profitable after years in the red). That shakeup also saw the announced departures of Robbie Bach, the unit's president, and J Allard, its senior vice president of Design and Development.

Enderle said: "With Apple trending to have a market cap higher than Microsoft's shortly, which is also a very likely trigger for this event, my guess is [Microsoft's] board and Gates have helped [Microsoft CEO Steve Ballmer] reprioritize this function and he appears focused on it now. He did a good job helping to drive the Windows turnaround; he may be able to do this as well."

Enderle also referred to the division as a "vampire" whose "profit, which wasn't much, was massively offset by the economic cost it caused to the corporation." The shakeup, he added, was "a stake driven through its heart."

(Enderle, if your phone's ringing at this moment: It's probably J Allard asking you to a one-on-one death-match in a steel cage, once he gets done with the off-road trucking he mentioned in his lengthy resignation letter.)

"Senior Vice President Don Mattrick will continue to lead the Interactive Entertainment Business, and Senior Vice President Andy Lees will continue to lead the Mobile Communications Business," Microsoft said in a statement May 25. Microsoft's refusing to tell me whether the Entertainment & Devices Division will even exist beyond July 1, when those two executives begin reporting directly to Ballmer, or whether its assets will be moved into other parts of the company--and given the silence, I'm beginning to think the answer to that question is, "Yes." Breaking up that division and having its people report directly up a pair of verticals to Ballmer would be a way to tighten the proverbial reins.

In any case, it seems as if Microsoft's preparing for a more concerted push into mobile and consumer products--look for its marketing campaign surrounding both Windows Phone 7 and Project Natal to be appropriately massive. If nothing else, its market cap is at stake.