It’s official: Microsoft’s latest operating system – Windows 8 - was launched last week and is now being used by thousands of consumers in-in-wild. Of course, you can find a ton of great reviews on the operating system (both the good and the bad) so we’ll leave the opining to the pros.

Instead, we’re going to discuss the testing considerations of Windows 8. As I’ll explain shortly, this applies to those of you who are  developing Windows 8 apps, as well as those who want to optimize your existing sites for the operating system’s touch-based functionality.

Since Windows 8 is only a few days old, I’m sure there will be a host of issues that will eventually surface (no pun intended), but for now, here are a few important things to keep in mind.

Live Tiles: One of the more unique features of Windows 8 is the customizable start screen with “live tiles” that convey information without ever having to run the application. For instance, I see the Twitter app shows recent followers, recent tweets, people that have rewteeted your posts, etc. For users of the Windows Phone operating system, these won’t be all that new. For developers, it’s important to test the functionality of your live tiles. Are they pulling the correct information? Are they updating on time? Are the graphics rendering properly? Failure to properly test these items will almost certainly results in a Windows 8 app that is not used or not pinned to the start screen.

Touch-Based UI: Although it can be used with a traditional mouse and keyboard, Windows 8 has been optimized for tablets and touchscreens. For mobile developers, the touch functionality is much the same as that of a mobile OS or an iPad or Android tablet (i.e. pinch, zoom, etc.). This functionality will have the biggest impact on those who want to optimize their current website for touch, which leads us to our next point:

Flash and IE 10: The launch of Windows 8 also ushered in Internet Explorer 10. While most of the features of IE9 will remain, there are a few new twists you need to keep in mind. Here’s a good tip from TechRadar:

“If you’re using Flash or any other plug-in platform, switch to HTML5. The new “modern” Internet Explorer won’t run plug-ins (including Microsoft’s own Silverlight). While it does have a built-in Flash player, it will only display sites that have been certified by Microsoft. If you haven’t been working with Microsoft to put together a touch-friendly version of your site, then you’re not going to be on that list. With IE10′s improved HTML5 support design tools like Flash and Silverlight aren’t necessary – and a site designed for IE10 will look the same in Chrome or Firefox.”

As I said before, this is just the tip of the Windows 8 testing iceberg. For more technical information on testing your Windows 8 apps, check out this post from Microsoft on their app certification kit.