There are several discussions currently taking place about various facets of the user agent (UA) in Firefox, Firefox for Android, and B2G. In case you missed them, here are links to the current discussions:

• Adding hardware tokens to the UA string – this is specifically in the context of B2G
• Touch or Tablet? – MS has introduced the “touch” UA token. Is “touch” useful in the UA?
• Custom UA whitelist – serve custom UAs to sites in order to get mobile content?
• Override the UA for bank sites – fix some broken bank sites due to a recent desktop UA change