The creators are trying the new app on the emulator because they need to know how textboxes will work with the new tool. If you already had used the textboxes then you already know how the pivot control works and it will be easier to use when you try to copy & paste text.
If you are a developer of WP7 mobile, then you need to download this tools immediately and try them. Here is a look at how copy and paste works in Windows Phone 7:
