Wouldn't the main cause if this issue be on web developers? Honeycomb uses 'Android' as it UAstring, and i thought phones use 'Android mobile'. Websites just need to adjust their classification just like they did with the iPad which uses adifferent user agent as well.
OK well scratch that comment. Looks like the UAstring is Android on both phones and the Xoom. The difference is the version specified.
user-agent: Mozilla/5.0 (Linux; U; Android 3.1; en-us; Xoom Build/HMJ37) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13
user-agent: Mozilla/5.0 (Linux; U; Android 2.3.4; en-us; SGH-I897 Build/GR22) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1