That's a good idea. If the search results page used the built-in ad_table thingy it could be made to sort on date rather than relevance, etc, without much work.
As far as portals go ... try searching for "new-portal". I get reasonably good hits on that.
The old portals package from Ars Digita sucked beyond belief and has been scrapped. "new-portal" is a new portals package written as part of the dotLRN effort. It's been partly refactored then abandoned by Open Force (the authors.) Because of this incomplete state we've not include it in our standard OpenACS 4.6 release. It's on my plate to finish it and integrate it into OpenACS 4.7, which we'll be working on again in earnest in a few weeks once dotLRN 1.0 and OpenACS 4.6.2 are released.
Yeah, this is as confusing as it sounds. We'd expected OF to finish the work last fall but it didn't happen, thus the disarray.
For now if you want portals you need to grab the package from dotLRN not OpenACS. It works with OpenACS just fine but there's very little in the way of admin UI to support cobbling together of portals for users. When the completed "newest-portal" package is released there will be upgrade scripts so you don't have to worry about being orphaned.
dotLRN has its own layer that automatically builds standard portals for classes etc but it's not been generalized ...