Back in 2009 I wrote a post entitled Twitter Event Hashtagging Strategies - see http://ukwebfocus.wordpress.com/2009/10/05/twitter-event-hashtagging-strategies/ - which touched on various points you've made in your post. The one suggestion you have made which I would disagree with is "Make sure the tags you use are unique" - nobody owns a tag and so it is not possible to guarantee uniqueness. I would suggest toning down this recommendation slightly be saying "Avoid using a hashtag which is currently widely used".

Thanks for the link to my post. I agree with your comment that "frictionless sharing was a good way of describing this lightweight sharing long before FB appropriated the term". If you've used the term in this context in your book, I'll cite it in the Wikipedia entry - especially since it has been suggested that the article should be merged with the Facebook entry. However when you go on to suggest that we should "Reclaim it!" you don't address the issue of possible confusion with those who equate the term with use in Facebook. I assume this is something we have to accept and part of the reclaiming of the term will be to promote the diversity of ways in which such sharing may be implemented - and also, as Pete Johnston pointed out, that not everyone will necessarily be happy with such sharing in all contexts.