"With WP7, Microsoft is trying to catch up to everyone else in mobile," said Zeus Kerravala, an analyst at Yankee Group. "In many ways, I think they've missed the mobile window, not to play with words. Windows Mobile has left a bad taste in people's mouths and, now, trying to get customers to try Microsoft and WP7 again will be difficult, especially with the popularity of Android and Apple."

Microsoft needs to replace those failed products with a "cool and sleek" set of WP7 devices "that will draw people in," Llamas said.

Microsoft is being quiet about the final lineup of devices that will be shown Monday, although a spokeswoman said there will be devices -- plural -- shown by Microsoft with AT&T, after a press conference with Microsoft CEO Steve Ballmer and AT&T Mobility President Ralph de la Vega. And Microsoft has not restricted itself to smartphones; some observers expect more news on Microsoft's plans for tablet computers.

Device makers HTC, LG and Samsung are expected to show off their new products at the launch event. Plenty of YouTube videos have been generated showing the distinctive "hubs" and "tiles" motif that will be used to distinguish WP7 from other interfaces. One the incorporation of five popular apps: Netflix, , Flixster, OpenTable and Travelocity. Another video, that shows , has received more than 400,000 hits on YouTube.

Also Monday, Microsoft will offer some hands-on experience with its consumer lineup, including WP7, Kinect, Bing, Xbox and "others," a spokeswoman said. A "global portfolio" of WP7 devices from various manufacturers will be shown in a separate location. On Tuesday, third-party developers will meet with Microsoft to learn more about WP7 on its final lineup of devices.