What's intriguing is that this will tie the data to the mail browser, rather than any mail or messaging application built into S60, WebOS or Android handsets. And the fact you can get off-line access now using POP3 or IMAP in these applications shouldn't come into the equation.
Desk-bound users had this feature turned on recently using the Google gears browser extensions, allowing off-line Gmail access, so this is a natural development. But with multiple ways of doing this, multiple teams working on the same solution, and all of them pulling in slightly different directions, is the attention to detail from Mountain view starting to slip?
-- Ewan.