I was cleaning up my hard drive today and found some screenshots I took of websites on 9/11, in Apple PICT format. Less than 7 years later, those PICT’s aren’t viewable on OSX in the Preview application (the standard image viewer). Seeing as this OS came out in 2005, it was likely abandoned then. At the time I was running the latest version of Mac OS 9, judging by the screenshots.
So, less than 4 years of support for that presumably very common file format.
I’ve converted the pictures to PNG (Using Photoshop 7, which can parse them), which as an industry standard open format ought to be recoverable for some time to come.
This has been reason #687 to avoid proprietary file formats.