Hi design folks,
2013/6/21 Erik Moeller <erik(a)wikimedia.org>
In case you haven't seen, User:Rillke on Commons
has implemented a
(default-on!) gadget that makes it possible to subscribe to
notifications of different types, e.g. policy changes, new features,
etc. These are shown as watchlist banners and upon login.
Here's a screenshot of the "subscription" interface:
IMO that type of gadget lends supports to the notion of shooting for a
subscription model to be ultimately integrated with Echo so that users
can get standard read-once notifications about things they care about
while keeping the core UI clutter-free.
Following up on this : the documentation is at 
On top of the topic feature mentioned by Erik, Rillke's watchlist notices
are loaded with other cool features, like built-in i18n, scheduling,
geotargeting (!), filtering per usergroup/browser/OS/language
And Rillke put together a kick-ass wizard to create such notices  - the
best way to walk into the above mentioned features.
(and the wizard itself is i18n using the Translate extension ^__^)
Hope that helps,