Thanks for the clarification, Ryan. This distinction isn't clear in
the original blog post. I also wasn't sure what the difference was
between me posting a message that I love Reebok shoes and Starbucks
posting they have a special on Frappuccinos. If advertising was
prohibited from Tweets, it would apply to commercial accounts as well
as individual ones. But you say that's not the case.
At this point, I'm not sure what services DO fall under the
prohibition guidelines but I guess they are ones where the users have
given advertisers blanket control to post whatever they want on their
Tweetstream. In effect, this sounds like advertising spam with a third
party taking over individual users' accounts.