A number of concept screenshots of early Metro concepts for Windows Phone 7 Series was published in the slides of the “Windows Phone UI and Design Language” session at Microsoft MIX10 this week giving us a rare peek into what Metro could have been.

If one thing’s for sure, large fonts and a text-driven layout was a sure-thing since the beginning. It appears they experimented with a much larger time display and diagonal-placed controls which look kind of cool but one could imagine to be a usability nightmare. Take a look for yourself.

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If a woman walking down a street didn’t do it for you, then a new Windows Phone 7 Series promotional video with a stronger emphasis on end-to-end scenarios was shown off at a Microsoft MIX10 session this week.

This Star Trek-inspired video takes you in to the lives of Anna and Miles, two made-up “life maximizer” personalities that the WP7S team uses to craft their product for. Scenarios demonstrated in the video includes taking and sharing a photo, playing games, messaging, social networking, searching and navigation. These guys obviously have a lot of free time.

As a great example Microsoft is still tweaking and crafting the Windows Phone 7 Series experience, a couple of new subtle yet “delightful” UI features was actually added to the build of the OS they’re showing off this week at the MIX10 conference.

The first of which in case some people are not very good at “spot the difference” and haven’t noticed what you’re suppose to be looking at is the new “Messaging” tile which has an emoticon that appears when you receive a new message. If that wasn’t delightful enough, it also changes as you receive more text messages – from a smile to a wink to a gasp.

Of course this demo build changes the emoticon with quite a small margin and this will be padded out in the final release, although I’m sure heavy SMS users will trigger all of the emoticons without a sweat.

The other change that has been implemented is “tile flipping”. Best illustrated with an example, tiles like a contact pinned to the Start screen will at times flip on its back like a card to reveal messages which in this demo is a Facebook status update.

I think this is a great idea to bring even more “life” into the already “live tiles” that exposes highly contextual information from services like a social network without any input or effort from the user. Delightful indeed.

Following a lead from a xda-developers.com forum thread whose users have analyzed the Windows Phone 7 Series emulator ROM with CSI-like forensics, a question that is now obvious in retrospect was raised, “are Microsoft’s own applications on Windows Phone 7 Series based on the same development platform it exposes to third parties, Silverlight?”

As I found out today at MIX10 the short answer is no, with a fairly legitimate explanation.

The reason the “default” applications on Windows Phone 7 Series are not built on Silverlight is actually a very straightforward technical problem, the applications were simultaneously developed with the platform and tools when they committed to building the operating system from scratch.

Although it might seem the grass is greener on the other side, Microsoft insists neither users or developers should be concerned as the public-facing Silverlight platform comes with no disadvantage to third parties.

In terms of performance, they state there is no discernible difference in the processing or rendering speed of third party applications. On the other hand, the breadth of APIs could have some differences but developers of other smartphone platforms like the iPhone face this too. Microsoft vows to surface additional APIs if developers voiced their needs.

Microsoft wasn’t able to confirm or deny the use of the “Iris” or UIX framework, but references to UIX in the ROM dump would strongly suggest so. Appropriately, Rafael Rivera is starting a series of posts that dives into the technicalities of Iris.

About six months ago at Microsoft PDC09, Dean Hachamovitch revealed Internet Explorer 9 for the first time and teased a relatively new browser rendering technique based on Direct2D, at the time. Barely weeks after, Mozilla also showed off their implementation of Direct2D rendering in a nightly build of Firefox.

Now at MIX10 Microsoft once again showed off a bunch of groundbreaking new (performance) features but I’m now skeptical second time coming if they’ll be as innovative when it eventually ships. Remember, even Internet Explorer 8 took the lead in terms of performance, when it was announced too.

In a press briefing I asked Dean if they fear the new features they showed off today could be implemented by other browsers that ship sooner, he responded “the Windows API is very rich” and he supports other applications who take advantage of them.

Of course this shouldn’t take away the fact that when Internet Explorer 9 will be great for end-users and the web as a whole when it finally ships, but by that time, it might be back right where it started – catching up to what is easily the fastest evolving industry in the world with an update cycle that doesn’t match.

We’ve survived Las Vegas and it’s day 2 of Microsoft’s MIX10 conference. The word of the day is “Internet Explorer” and the number is 9.

To bring you the event live, join Ed Bott, Mary Jo Foley, Kip Kniskern, Benjamin Rubenstein, Paul Thurrott and myself in our hallmark group liveblog. Audience participation will be enabled by default so feel free to ask questions and provide your thoughts on the announcements live.