Visual Studio 2015 RTM has been released and is available for download from MSDN if you have a subscription. The Community Edition is also available. The UWP (Win 10 Universal Apps) bits aren’t there yet though.
Link to community edition: https://www.visualstudio.com/downloads/download-visual-studio-vs
This replaces Ultimate version of Visual Studio
Universal Windows Platform (UWP) apps are the new Universal apps. You have one project that you can build for the various Windows 10 platforms (desktop, phone IoT etc.) A blank UWP app without any extensions will build for x86 and for ARM and run on any Windows 10 x86 or Windows 10 ARM target respectively. Without extensions it uses the Windows 10 Core which all Windows 10 targets implement. There are then extensions for the desktop, mobile (phone) and IoT which when added to a blank UWP project specify the target.
The templates for the UWP apps HAVE NOT BEEN RELEASED with Visual Studio 2015 RTM. They will come as SDKs and be released about the time that Windows 10 RTM is released (scheduled for July 29). There will be the Windows 10 SDK and the Universal Windows apps tooling for VS 2015.
You need the new version (for VS 2015) of Remote tools if you are developing for a remote device, eg an IoT device.