Betwixt and between ODF, OO-XML, and Google, Corel discusses Wordperfect roadmap
Until very recently, if you or your company wanted to buy a "productivity suite" -- a package of software that includes a word processor, a spreadsheet, Powerpoint-like presentations, and a few other helpful utilities -- there were relatively few choices and none of them played well together. In other words, while you may have been able to open documents that were saved in one suite using another suite, that "interoperability" was never quite perfect.