Answering would be cool. If you set the subject to something like "Incoming SMS ##<number>#" it would be easy to
- answer to a sms (some cleanup of the body before sending the sms would be cool)
- write a new sms using this method
However, care should be taken that, if incoming and outgoing e-mail-account are both set up in maemo's mailer, an incoming sms is not treated as an outgoing one.

Additionally, the e-mail receive intervall should autmatically be shortened while the application is active.