Microsoft has released out of beta the HD Photo Plug-in for Adobe Photoshop. 

The HD Photo plug-in supports a wide range of pixel formats (including high dynamic range, wide gamut formats) and numerous advanced HD Photo features.

This plug-in is designed for use with the CS2 or CS3 versions of Adobe® Photoshop® software running under Microsoft Windows XP or Microsoft Windows Vista. Any other use is not supported.

Download

Alternatively, if you are a Paint.NET user, you can get the HD plug-in for it here