The partnership between Arduino and Microsoft has been announced in April at Build 2015 and now Windows is first certified Arduino OS. Also, Windows introduced Virtual Shields for Arduino for easy wireless connection to Windows 10 devices and Remote Arduino, with which developers can "(wirelessly) access the capabilities of  Windows 10 devices as if they were physically attached to an Arduino Shield". There are some updates from Windows blog interesting for Arduino fans:

Now you can get the Windows Insider Preview of Windows 10 IoT Core with the next four technology investment.

1)Windows 10 IoT Core Universal Windows Platform (UWP) support for Arduino Wiring

2)>Windows 10 IoT Core Universal Windows Platform support for direct memory mapped UWP Providers

3)Windows Store availability of the Windows Virtual Shields Application

4)Windows Store availability of the Windows Remote Arduino Experience Application

Arduino Wiring
We want to make it easy for you to use existing Arduino Wiring Sketches, libraries, and hardware with Windows 10 IoT Core Universal Windows Apps(UWA) on a Raspberry Pi 2 or other supported board. By creating a new Visual Studio template, supporting NuGet Packages, and platform improvements we’re making it easier than ever to build on Windows 10 IoT Core.Simply drag-and-drop (or cut-and-paste) your favorite and readily-available Arduino Wiring INO and library files into Visual Studio, connect your hardware over GPIO, SPI, I2C, ADC or PWM to your Raspberry Pi 2 or other supported Windows 10 IoT Core device, and run your code. Visual Studio and Windows will do all the heavy lifting to create a UWA and deploy it on your behalf, and you can also leverage the power of Visual Studio with Windows to debug your Arduino Wiring code.
With Arduino Wiring being supported as an extension to the Universal Windows Platform, you can even create a UWA that combines Arduino Wiring, C# and XAML. This enables you to build great projects with mixed mode programming like the plotter near the end of this video. Try out Arduino Wiringhere.

Windows Virtual Shields for Arduino Application
This technology lets you leverage sensors and actuators on your Windows 10 device from an Arduino over USB, WiFi, and Bluetooth. For example, you can access your Windows 10 Phone accelerometer or your Windows 10 Desktop Screen from an Arduino over WiFi.
The Windows Virtual Shields for Arduino application is now in the Windows Store, and has improved the workflow to get started. The app is all you need on the Windows 10 device. Try it out here.

Windows Remote Arduino Experience
This technology lets you develop on your Windows 10 device and access the physical world via an Arduino over USB, WiFi, and Bluetooth. For example, you can program in C# on your Windows 10 Phone and drive a servo connected on your Arduino over Bluetooth.
We also created a Windows app that enables you to explore GPIO, ADC, and PWM functionality without writing any code on your Windows 10 device. TheWindows Remote Arduino Experience app is now available in the Windows Store. Give it a try!