If you implement it and want to contribute it to the project under the CPL, then you can send it to me when its finished and I will review it and consider it for inclusion into the core package or make it available as a separate download. If its implemented for all the data layers its easier to include in the core.
Several people have talked about implementing a News Feature which I think is the same thing as an Announcements Feature.
As I discussed at the bottom of this thread, what I would really like to see is an advanced feed aggregator that allows selectively publishing individual items from a set of feeds. In this way announcements could be pulled in from any feature that exposes a feed. I would like to make more of the features expose a feed so that Announcements could be pulled in easily from a blog, an html module, a calendar event etc. This way the announcements content would just be re-used directly from its corresponding feature. So this advanced feed aggregator could easily be used for Announcements as well as other things.