There's more stuff out there on RSS and bandwidth:

RSS Bandwidth Usage We're all starting to see the inevitable issues with RSS bandwidth usage. Something that occurred to me in the shower that I haven't heard anyone talk about (although I am a veritable newbie compared to people like Dave Winer, Ben Hammersley, Bill Kearney and others) was can the feed itself specify the allowed polling interval ? I.e. if you're me and you update your blog constantly then I'd want to allow a fast polling interval but a lot of us don't update as frequently and they could set a daily interval. Or has this been hashed out, discussed and I'm just clue free ? And yeah I know that some aggregators would ignore it but it could be implemented as a default setting that the user manually forced if they needed to. The same way you can force a browser to refresh.

IMHO, the whole feed polling thing is a hack. BottomFeeder supports it, but there's a simpler answer (which Bf also supports) - conditional-get. You send a small query to the Http server and ask if the doc has been updated. If it hasn't, you get a documented answer, and you don't fetch the whole ything.

This is the prior art - it was invented years ago to solve scalability issues at the server. Http already has an answer to this problem. the various proposals to implement hacks with update intervals on fully dynamic feeds will make the problem worse, not better - let the Http server do what it's good at, and push out a static feed. Have aggregators do the right thing, and check for updates before pulling the whole feed. It ought to be simpler to have aggregators support the existing infrastructure (which works, btw) than to support some new thing which purports to solve the same problem.