It would be awesome to have a mail app for Mac OS X that included all
the cool features such as steams, calendar, tasks, contacts, etc.
Most people prefer native apps, rather than running it through a
web browser. I know that we can use the IMAP, CalDAV, etc. but having
everything in one app with the added benefits of streams, etc. would
be much much better.
This could start out as mainly a web portal app but the
difference being that it would work offline too (then gradually adding
in more native os x features).
Keep up the good work!