IIRC, hasn't it already been cryptanalyzed and broken?

Personally, what I'd define as secure enough would be messages encrypted end-to-end with each message rekeyed via Diffie-Hellman key exchange.

That'd be really coo- oh wait, it exists, and is vetted by some serious names in the security industry.

Cyanogenmod already integrated secure messaging into the ROM, it'd be nice if Maemo/MeeGo users could join in the fun.