Not really that is still as good/bad as .PSD is because of the nature of what the file is used for. They are both primarily containers for unfinished works and are designed to hold a lot of detail without so much regard for size and portability. Of course the .XCF format is open but not good enough for a simple viewer or even a web browser. Some file format based on SQLite will probably be more viable as a cross platform image format that is extensible beyond any one software developer limiting it. Kind of like HTML.

It meets all of the requirements of the parent post I replied to, plus it even has a pretty decent open source editor. It's internal structure may not be in SQLite format, but it is an extensible tag based chunk format. You shouldn't dismiss it so easily.