The Microsoft executive who has overseen development of its popular Exchange communications server software for the past seven years will take over the reportedly-troubled development of Windows Mobile.

Terry Myerson will become corporate vice president of the mobile communications product group. The 11-year veteran replaces corporate vice president Todd Warren, who will stay on at Microsoft as corporate VP of technical strategy, a spokeswoman said.

Myerson, who oversaw development of Exchange Server 2003 and Exchange Server 2007, will report to Andrew Lees, senior vice-president of the mobile communications product group.

Microsoft released Windows Mobile 6.1 in April. It has not said when Windows Mobile 7 will be released. But CNET News.com, citing unnamed sources, reported last month that Windows Mobile 7 will arrive in the second half of 2009 instead of the first half of the year, as originally scheduled.

Windows Mobile is the third most popular smartphone operating system behind Nokia-backed Symbian and RIM's BlackBerry platform. More than 18 million Windows Mobile phones, such as HTC's Touch, have been sold.

But Windows Mobile has lost mindshare to Apple's iPhone, and is in danger of being eclipsed in terms of market share.

Last month, T-Mobile also launched the G1, or Google phone, the first to run the Google-backed Android OS.

Some hope that new features in Windows Mobile 7 could help the OS regain its edge, however.

During his time as Exchange's development chief, Exchange cemented its lead over IBM's Lotus Notes/Domino as the most popular e-mail server software.

Besides Exchange, which he had overseen since 2001, Myerson has also "guided the development" of six server products, including Microsoft Site Server and BizTalk Server.

Rajesh Jha, corporate vice-president of Microsoft Office Live, will take over development of Exchange, according to a Microsoft blog.