Yeah I'd be really surprised if you found a way around it as the Flash plugin itself can report the operating system of the user independently of what the browser is reporting. It's possible that hulu is only checking the browser user-agent string, but I doubt it.
Anywho, good luck, be curious as to your results.
FWIW, I just got a major (90MB) Maemo update last week...Flash sites running/loading noticably faster, as well as Firefox browser. I haven't looked into the browser extension "spoofing" but hulu/abc.com, and the like, are still reporting that either my browser or OS is not supported (site looking for PC based OS to install plugins).
If nothing else, hardware wise, the Droid shoud be able to make full Flash sites usable.