Although I have noticed a massive jump on the sites I have promoted via Twitter on search engines .. it would be reasonable that blogger would view some twitter feeds and emails as spam.

Just going through some search engine results about blogger and twitter spam showed that more then just a few people are worried about that.

Cross promotion is great but remember, some of these sites are still not owned by Google so they need all the traffic to stay on their site (till google buys them).

Great comment though. I never though much about that till you mentioned the issue.