Apparently RSS 2.0 came out last fall and I missed it. Great improvements over the earlier specs (was there ever a 1.0? Seems like we went from 0.92 to 2.0….).
You can tell aggregators to skip certain hours and certain days when you know you won’t be updating, you can provide the URL to a registration service to have updates pushed to you, specify a TTL (time-to-live) for your content, etc. (of course, all this stuff may have been in earlier specs and I just wasn’t paying attention).