This tombstone idea is great for deleting posts and especially useful for those cases where you publish an item and then immediately delete it in blogger. I think the delete post button in blogger should have a big huge warning that you're only deleting it from your site and that a copy of this post likely lives in many feed aggregators, especially Google Reader. Alternatively the delete button in blogger should also make a tombstone for the post in the feed. But it doesn't, so oftentimes you post a post, delete it and then end up seeing the post in your rss reader anyway because the moment you posted, something pinged something else (perhaps via pubsubhubbub) and bam your content was fetched via rss/atom.
O.K. that was a long winded statement of the problem, hopefully it had enough keywords to catch the searchers out there. Here's how you delete a post from Google Reader, first the theory, then the tool to make it easier.
You can get a feed directly from Google Reader with a URL like this. Just URL escape the feed location and add it to the end.
Inside that feed is an element like this:
can page further back by taking the gr:continuation value in the
response and adding it as a ?c= query parameter.
is a program that will fetch ALL the feeds just give it a feed URL
if you're looking to obliterate a secret from your blog....
(fgrep -l secret *.[0-9][0-9][0-9].xml | while read fil; do xmllint -format $fil | egrep 'original-id|secret' ; done) | less
then make a new feed with those guids and an empty (I use a single space) subject/body/link