Yes, perhaps not your commonplace kind of question - but I brought it up on a recent episode of the MuggleNet podcast, Alohomora! In addition to a great deal of speculation on this question and others in our new forums, one of our most active commenters, Hippogriff, has written a quibble entirely about how Floo Powder might work. He even takes a shot at answering my question:
...its important to remember that wizarding owls seem to be much more intelligent and have a better sense of direction than our regular Muggle owls do. Therefore, it might be possible, with a little determination, to train these owls to use the Floo Network as wizards do. The only problem would be the naming of the desired destination, as “hoot” will not always cut it. So, a modification might be possible to allow the wizard sending the owl to say the name, and trust the owl to get out at the right time.
Our quibble this week is yet another essay that comes from our Alohomora! section on MuggleNet, where fans can discuss the newest podcasts and also discuss aspects of the chapters we analyze each week. It's a whole lot of fun, and if you'd like to submit a quibble to us to possibly be featured, right here on this page, you can manually publish your work on that part of the site, or submit in an e-mail to me at firstname.lastname@example.org.