There are few file formats ubiquitous as JPEG (ASCII text comes to mind). It's almost universally compatible, available in every image handling application you could possibly want to use and, it works swimmingly well. Who could possibly want to change all that? Microsoft, that's who.
Last year Microsoft began promoting its Windows Media Photo format, recently renamed HD Photo (ostensibly to gain a little street cred from public familiarity with HDTV), as a "better" alternative to the standard JPEG. According to Microsoft's specification literature, HD Photo gives twice the quality compared to JPEG at similar file sizes. Vista includes built-in support for HD Photo and, Microsoft has been actively promoting HD Photo to camera m anufacturers as a superior alternative to the aging JPEG specification.
Sounds great, where's the catch? Licensing. Patents surrounding JPEG have expired, meaning if you want to include JPEG support in your application, and be universally compatible with other applications supporting JPEG, you don't have to pay fees to any company or individual. HD Photo is a published standard, but it's owned by Microsoft lock, stock, and barrel.
If you want your application to be compatible with cameras that use HD Photo, you'll need to sign a deal with the boys in Redmond, and pay the license fees they demand for the privilege. If widely adopted, HD Photo could spell big trouble for compatibility on Open Source platforms, or any platform Microsoft feels presents an undue competitive threat.
Update : HD Photo is licensed under the Open Specification Promise, under whic h Microsoft vows not to enforce its patent rights as long as developers conform to the specification. Thanks to Bob for straightening me out!