Microsoft is opposed to Apple's App Store trademark

Apple’s ( rather old ) attempt to register the App Store trademark was met with hostility by Microsoft, which considers the phrase “app store” too common and already common for many online stores selling software; so it would be unfair if many companies were forbidden to use this phrase to describe their services overnight.
Microsoft insists that the word “app” is commonly used as an abbreviation for application when it comes to software; not to mention “store,” meaning “a place where goods are sold.”

Apple filed an application to purchase this brand back in 2008, a week after the opening of its App Store for the iPhone. It is reported that there was also an attempt (which met the failure of the relevant authorities) to register the concepts of “The Computer Store” and “Log Cabin Homes”.

As another argument, Microsoft mentions that Steve Jobs himself in an interview in October 2010 used the phrase "app store" in relation to other companies. Here is an excerpt from that interview:
In addition to Google's own app marketplace, Amazon, Verizon and Vodafone have all announced that they are creating their own app stores for Android. There will be at least four app storeson Android which customers must search through to find the app they want and developers will need to work to distribute their apps and get paid.

Microsoft also provides statistics on the use of the phrase “app store” in the media in relation to different companies:


Finally, I want to remind you that Microsoft opened its App Store for Windows Mobile in October 2009.