Sam Steingold wrote "No Proprietary Binary Data Formats" [2/7/00, last updated 4/27/03]. He is making a slightly different point, that binary formats are bad (because you can't use tools like grep and diff). I agree with that statement, although it's not my goal with ODFI. For example he thinks PDF is bad and any XML format is good. He does not mention RTF (which is text-based and standardized).
Jeff Goldberg, with his "MS-Word is Not a document exchange format" [5/1/03], is against the use of Word attachments in particular, in a similar vein to Richard Stallman's complaint. He feels that a documented binary formats such as PDF is OK (which I agree with).
I'll throw in Scott McNealy's The "Case for Open File Formats" [10/12/01], even though he is Scott McNealy. As he writes, "Look at it this way: The data you put into a spreadsheet is yours. The content you put into a business presentation is yours. It's your intellectual property, right? So why would you allow any of it to be held captive in a proprietary file format?" Excellent point, although the article is really a plug for Sun's use of XML. I'm not sure XML is the magic solution. I'm sure someone could come up with extremely obfuscated XML if they wanted to. Plus, Microsoft can't make XML the standard "Save" format for a while, or it would require everyone in an organization to upgrade once a few people do (which is something Microsoft gets accused of doing with evil intent). What you really need is documentation (which Sun, to its credit, does have for its XML format).
Finally there is this article by Ramon Flores, which is in Portuguese, but has some good links at the bottom (including one to my original ODFI article). Actually there is a high degree of inter-linking between all the articles listed here.