Yes, the latest docx file format is supported by QuarkXPress 10.
QuarkXPress makes it easy to import, export, and edit text in a wide variety of formats. You can drag and drop text files into a layout and use Story Editor view for maximum readability. When working with Microsoft Word, import text, style sheets, pictures, and hyperlinks.
With QuarkXPress® you can save time placing text in your layouts by avoiding copying/pasting. You can import text directly into your QuarkXPress layouts from applications such as Microsoft® Word, retaining the original formatting.