On one side you have Adobe, that succeeded is providing a fully-disclosed portable file format, PDF.

On the other side, you have Microsoft, who do not like to not have a dominant position on a market, that decide to run after PDF with Metro, a new XML based file format that will be licensed royalty free and (that) users will be able to open Metro files without a special client according to their CEO. The problem is that Microsoft is notorious for patenting everything and make sure you only get crumbles from the cake, so, despite that we don't have anything yet but some PR, I wonder what they will come up with.

The Metro technology is likely to go head-to-head with Adobe's PostScript technology. "It is a potential Adobe killer," said Richard Doherty

We already heard that a 15 years ago when Microsoft worked on True Image to have a replacement for PostScript. PostScript is still there, and from True Image, there is only one thing left: TrueType that Apple had developped and sold to Microsoft in exchange of the other technology. The only other postive effect of this battle is that Adobe ended up disclosing the Type 1 PostScript font format. But now, there is nothing to disclose as both PostScript and PDF are completely documented and free to use even if still the property of Adobe.

Update: I still have to find any patent issue associated to PDF.