We have an application that is still actively developed by the vendor that requires SQL2000 compatibility. Well, we're moving to SQL2012, which no longer has compatibility that far back. For that, and many other reasons, we're migrating to a different product.
What gets me is that these vendors always act surprised that their stuff doesn't work after the latest version of Windows/IE/SQL/Whatever is released. It's as if they ignore the fact that there are at least a years worth of CTP and Beta releases. Add to that the fact that for stuff like the SQL2000 compatibility, Microsoft has been telling developers that it's going away for a long time. There's always several stages.
You shouldn't use feature/API x
You shouldn't use feature/API x, because we're going to deprecate it
You shouldn't use feature/API x, because it's now deprecated
You shouldn't use feature/API x, because it's now deprecated and we're going to remove it altogether
You can't use feature/API x, because it's gone
Yet, vendors seem to miss all of this and then act indignant when their stuff doesn't work.