Using Word instead? No problem. You could import Word into Google Docs, then export from there (the format must be newer than the one for the Microsoft 95 version of Word).
Among other major importable formats for Google Docs are HTML, .txt and .odt.
No, Random House isn’t likely to rely soon on Google Docs’s ePub export. But if you’ve just finished your novel or Ph.D. dissertation and want to beta-test it on friend, then Google Docs’ ePub capability could be handy.
Same if you’ve written a corporate training manual that you want employees to be able to read on their iPads or iPhones.
I tested this with a copy of The Adventures of Huckberry Finn in the text format from Project Gutenberg, and sure enough the results were readable in Calibre and Marvin on my iPad. Line breaks went astray. But I could have cleaned that up before the conversion (I’m in a hurry).
Here’s the command to reach the ePub export feature of Google Docs: File menu > Download as > EPUB Publication (.epub).
OK, good job, Google. Now when are you going to give us not just an ePub exporter but also stellar ePub editor?
Reminder: For more polished ePub for free, you could try Sigil.