I do think the forum should have integrated changetip or something similar, it just makes sense. We are the bitcoin forum after all, and quite honestly I wouldn't consider changetip bot posts as spam if they were single line and only showed for a minimum amount ($?). If they're annoying, they can be ignored, or even set as default ignored by everyone.
Why not just implement a script that adds an icon on each post that when click opens to a screen with the users public key asking how much you would like to send to the user, and then you just click send and the user gets the btc sent to their wallet and also a PM from the forum saying they've been tipped with a pleasant chirping sound when they log into the forum alerting them to their new tip they've received.
Changetip seems unnecessary if the websites implement these features themselves.
Because then you might as well just have a bitcoin:address link in sigs or on profiles. The main feature of changetip is its a social and public appreciation.