Following the unveiling of the new Windows Mobile 7 Series in Barcelona this morning, Microsoft held a press briefing in Redmond where we spent time checking out one of the phones. See a demo above from Microsoft's Gian Wilson, and continue reading for more information and impressions we gleaned from the briefing.

Microsoft will use the Windows Live ID system as a log-in for the device at the system level, not just for individual features or apps. That's apparently one reason you don't see people logging into Xbox Live in demos of the phone; they're already logged in via the system. The approach is similar to Google's model with its Android-based mobile devices, which use Google accounts.

Microsoft isn't going into a lot of detail about which Xbox Live games will be available on the device, and in what form. The company's ability to interest those 23 million Xbox Live members in the new Windows phones will be a key factor in the fate of the phone, so those details will be important to watch as they unfold.

As you can see in the demo, the "live tiles" on the home screen can be arranged in any order the user wants, and the company says there's no specified limit to the number of tiles people can have. Those that don't fit on the initial screen can be accessed by swiping up on the touch screen, much like scrolling down a web page.

As we noted earlier, the "Windows Phone 7 Series" name is a real mouthful, and doesn't exactly roll off the tongue. You'll hear me struggling with it in the video. One problem from a linguistic standpoint is that people are just getting used to the idea of "Windows Phones," and the brand is not yet established enough to support verbal appendages at this point. Will be interesting to see how Microsoft markets the devices to consumers. One possibility is to just call them "new Windows Phones."

Speaking of the Windows Phone 7 Series launch, keep in mind that for all the attention the phones are getting now, the first of them won't actually be available on the market until late this year. I asked company representatives how they could possibly get anyone to buy Windows Mobile 6.5 devices in the meantime, given the size of the leap that will be coming later in the year. Despite my skepticism, Karen Wong Duncan of the Windows Phone team expressed confidence that the breadth of existing devices will be attractive to people. She cited as an example the well-received HTC HD2.

One of the most interesting aspects of the new phones is the way Microsoft is attempting to give people an alternative to apps -- not doing away with apps, but creating "hubs" that pull together specific types of information and media from different online services. The "people" hub, for example, can pull information about specific contacts from the phone, Facebook, Windows Live and other sources.

Previously: Bloggers gush over Windows Phones, except for clunky name; and Microsoft's new Windows Phones add Xbox, Zune, 'live tile' design.