With the new stable version 2009.2 of the eZ Components, the Document component get support for the OpenDocument format. You can convert OpenDocumentText (ODT) to the internally used Docbook XML and from there to any of the other formats supported by the component (like RST, Wiki markup or ezxml). The other way around works in addition, read any format supported by Document and convert it to ODT. You can nicely style the generated document using a CSS sub-set and even generate a PDF with the very same style settings.
I wrote up a tutorial this new feature of the Document component on my blog, where you can also download example source code and examine the results of conversions.