Technically, wise guy, I can (as the publisher and one of the original creators of Fate, as well as a guy who has read the rules), and this has been the ruling we've put down about tagging for effect for several years now.
Merge the understanding of what a tag is (a free invoke) with the language about compelling other aspects on I believe YS107 and I believe the findings are clear.
I am not being a wise guy...just perhaps a bit pedantic.
Hmm, rereading it again, I suppose the rules seem to indicate there are Invokes, Invoke for Effect, and Compels, and tagging only allows the first one. Whether right or wrong, that's what the book says. If you say they are all supposed to be the sort of thing you can invoke with a tag, then I suppose that should be something put on some errata at some point. Perhaps calling using a tag an Invoke, then have something like Invoke for a Roll (either +2 bonus or reroll), Invoke for Effect, and Invoke for a Compel.
Again, being a bit pedantic here.
Edit: Perhaps we should make a sticky and put stuff like this there. Unofficially Official Errata (and Clarifications) or something? (Or I suppose it might as well be official).
Edit2: If you want, I could comb through your posts and see if other things pop up and make a post with all that stuff, though perhaps someone who has been here longer would be more familiar with it.
Edit3: Or I guess you could expand on it from the tag angle, Tag for Invoke, Tag for Invoke for Effect, Tag for Compel, but I thought moving everything under "Invoke" made more sense when I wrote the above.