Wikipedia has hundreds of wonderful portals on every imaginable topic. These are perhaps one of the most underexposed treasures on the site. It would be lovely if people could subscribe to a portal feed, or individual "boxes" (typical portal arrangement is into rectangles with different content). Example: http://en.wikipedia.org/wiki/Portal:Free_software
How could this be achieved? One way would be to support an RSS extension that would operate as follows:
1) You put something like
<makefeed> title=Selected article on free software addto=freesoftware.xml addto=freesoftware-sel.xml </makefeed> <feedicon> feed=freesoftware-sel.xml </feedicon>
inside a template, or indeed any page.
2) When a user edits a page, the extension checks for the presence of <makefeed> in the wikitext. If it is present, it adds a
( ) Add as new item to RSS feed ( ) Update most recent RSS feed item for this page (x) no change
selection to the page, below where the minor edit checkbox is. This selection should only be available to users with a definable permission level (e.g. autoconfirmed).
3) The feeds could be directly updated/written on the disk, in the images/ directory. In any case, the <feedicon> tag would generate a pretty link to a feed with a given name.
The feed content would be the action=render output for the page where the <makefeed> instruction is found (ideally sans noinclude). It could also include the edit summary.
Given that a feed could be accessed from multiple pages, you could build aggregated feeds (in the above example, freesoftware.xml would be a feed for the whole free software portal) and individual ones (freesoftware-sel.xml would only be the selected article box). You'd have to do some clever scanning of the file on disk to make safe updates, but it shouldn't be too hard.
Any conceptual flaws? Any takers? I think this could really make a big difference for content re-use, not just in the context of Wikipedia. But the portals seem like a particularly attractive target application to me.