If you’ve been paying attention to Mobile World Congress at all today, you’ll find that the big news is Microsoft’s Windows Phone 7 Series (as they are now calling it). This is the latest version of Microsoft’s phone operating system and it is a pretty big change from the previous version. A lot of people are hoping that this will raise the bar for what people expect from a Windows Mobile phone, and update the OS to be competitive with the rest of the players (iPhone OS, Android, Palm WebOS, etc.) Microsoft has thrown away just about everything from the previous version and started anew which a highly animated and stylistic interface (it’s about time.) If you’ve used the Zune HD, you might recognize many of the interface concepts. Check out a video below:

I could tell you guys and gals all about Windows Phone 7 Series here (annoying name, isn’t it?) but the folks over at Engadget are already all over WP7S with plenty of great pictures and videos, so I’ll let them take over in that regard.

What this post is here for, however, is to theorize what this may mean for the MID/MIDPhone segment. What’s interesting about Windows Mobile is that the OS has never really been featured on any modern media-centric devices that aren’t phones. Considering that the word “phone inch is actually in the name of Microsoft’s latest version of Windows Mobile, it’s unlikely that we’ll see it pop up in non-phone devices. Is Microsoft creating a silly artificial limit by dedicating this OS to phones? Possibly.

I can’t imagine that they don’t want as much consumer mobile device market share as possible. Take Android for instance — it is the OS of choice on just about any MID (and plenty of phones as well) these days. As smartphones and MIDs continue to meld together, WP7S might just get edged out if they don’t open it up to other devices. Perhaps MS wants to protect the image of Windows Mobile this time around by only letting it run on approved devices to ensure a great user experience? We’ll have to wait to see exactly what happens, but I think MS will be running into a wall of questions such as, “What exactly constitutes a phone? inch, as we head into the future. Will a device that relies exclusively on 3G for VoIP calling be considered a phone in Microsoft’s eyes, and thus be allowed to run WP7S?