Google Android dev team describes some issues when browsing websites with mobile variants using large-form-factor Android devices.
Currently, Android devices provide following (in addition to standard info) in the User-Agent: "Android", a version number, a device name, a specific build, Webkit version info, and "Mobile". For e.g., Froyo on a Nexus One has following UA: Mozilla/5.0 (Linux; U; Android 2.2.1; en-us; Nexus One Build/FRG83) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
The "Mobile" string in UA indicates that this device would prefer a version of the website optimized for Mobile (small form factor devices), if available.
"We recommend that manufactures of large-form-factor devices remove "Mobile" from UA, and keep the rest as currently implemented. Web sites can then key off "Mobile" in UA to decide on which UI version to present to device. So a large screen device running Froyo would have a UA similar to: Mozilla/5.0 (Linux; U; Android 2.2.1; en-us; device Build/FRG83) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Safari/533.1
Where "device" would be replaced with actual name of the new device. Sites can continue to use "Android" in the UA to optimize for Android specific features and can also key off of "Mobile" to determine which UI to present," explains Google.