If you haven't seen the recent Microsoft Interoperability announcement, I suggest you read it. It's been Slashdotted, so I figure there's a decent chance that everybody on the Internet has seen it already. This is, of course, an extension of the Microsoft Office Binary Formats release of a few days ago, and I'm equally leery about it. There are some interesting comments on the Office Binary formats on the web, including these by Jeff Licquia, and those he links to by Joel Spolsky.
On the one hand, this is an amazing opportunity for F/OSS developers and pretty much everybody interested in cross-platform interoperability. There are probably quite a few OpenOffice.org developers that would have killed to get free access to the specs for MS Word and Excel files over the past few years, considering how close to impossible it must have been to reverse-engineer everything. And, if it pans out, I'm sure that this will lead to better Microsoft format compatibility in the future years. If it pans out. For one thing, the specifications are immense and ridiculously complex, and I don't know if anybody's going to bother including Lotus 1-2-3-compatible Excel format importers in OOo. The somewhat more serious concern is whether the "Microsoft Open Specification Promise" is acceptable. IANAL, but it seems that this prohibits implementers from ever filing a patent infringement suit against Microsoft for related technologies, which might be a stifler, particularly for commercial competition like Corel WordPerfect. But, hey, maybe I'm reading it wrong and it's all good. Maybe we'll see a better Wine, OOo, AbiWord, and everything else tomorrow. I just don't know.