I think that the problem there was posterous didn't communicate this to their users.

Reddit does a fantastic job of communicating with the users; if they explained what was happening, I think the users would be fine with it.

I agree, I especially think that Redditors would be happy to support Reddit in a way that leaves them with the same amount of money, Amazon with less and Reddit with more.

If they announce it and add a setting to disable it, I doubt their users would complain. Seems like a really good idea

Livejournal did this in 2010 and their regexes were pretty bad redirecting GlutenFreeBay.com to ebay.com thinking they were changing affiliate parameters. http://news.ycombinator.com/item?id=1168331