Much to the chagrin of Microsoft CEO Steve Ballmer and Devices and Entertainment honcho Robbie Bach, the Wall Street Journal reports that even publicly stomping on employee iPhones hasn't stamped them out:

Nearly 10,000 iPhone users were accessing the Microsoft employee email system last year, say two people who heard the estimates from senior Microsoft executives. That figure equals about 10% of the company's global work force.

Outside of specific development units like Bing for iPhone, while using an iPhone at Microsoft isn't forbidden, it's discouraged. Microsoft will only re-emburse expenses for Windows Phone-based devices. Likewise, several executives have spoken out against using iPhones, including Ballmer who quipped that his father worked at Ford and so his family always drove Ford.

While a few use the openly, others hide them in generic cases -- or make sure not to answer them if they're in a room with Ballmer. (Or use them if they're a member of the Gates family!)

Apple employees, of course, are not thought to be using Windows Mobile devices in any perceptible quantity. Could Windows Phone 7 Series change that...?