JPEG is an open (by the old definition) standard. Anyone can get the spec to it and write an implementation. In fact, there exists an implementation that is all but public domain and definitely open by the newer definition. .xls is not an open standard by any definition. Microsoft will not describe the format to anyone. Any of the current non-Microsoft programs that can read .xls documents can do so only through reverse engineering, and can, therefore, be considered illegal. Furthermore, Microsoft does not produce anything that can read .xls documents except on Windows and Macintosh, including their free readers.

I'm not bashing Microsoft because it's fun or it's the hip thing to do. In fact, I'm not bashing Microsoft at all (at least not here). I'm just stating that one of the primary reasons that they are able to retain this monopoly is because they've trained everyone to rely on their products, to the detriment of anyone who wants to use non-Microsoft products. I could go into serious Microsoft-bashing mode here, but I won't, as that's almost totally a religious debate. (This isn't even the Off Topic forum, for God's sake! ) However, posting proprietary formats to someone that you don't know for sure can read them is not the right thing to do.

By the way, I'm seriously not trying to degrade thinfourth2 here. I'm sure that he thought he was doing the best thing. And that's what makes this all so insidious.