Should I check with collaborators before presenting unpublished material? I've been working on a paper with some collaborators.  Barring a breakthrough on some unresolved questions, the math content is finalized.  I would like to give a talk on the results, but I am unclear on the etiquette.  Should I check with my collaborators before presenting the material?
In general, how careful should I be discussing and presenting unpublished material without clearing it collaborators?
 A: Check with your collaborators on this one. Opinions vary.
A: I think in this sort of case it is always "better safe than sorry". I can imagine all sorts of issues that might occur (though not necessarily) if you do not ask your collaborators. For instance, perhaps one of them feels that it would be premature to expose the work to a general public at this point. Perhaps someone's feelings might get hurt just because they feel you should have asked them when you didn't. 
On the other hand, if you do ask your collaborators, the worst thing you lose is a few minutes of conversation or email. It might also benefit your relationship with them as they would feel you respect them and that they can count of you. If they don't care about it, no harm done.
A: Definitely check with collaborators prior to presenting unpublished work which you are all working on trying to publish together.  In other words, a formal collaboration with intent to publish a joint paper, or intent to present at a symposium or seminar, pretty much states that you are working together.  You don't want to appear ungracious or try to "scoop" credit.
In medicine, there is also the problem that journals do not want to accept "previously published" work, and some journals define presenting at conferences as prior publication, whereas other journals (Journal of the American Medical Association) state specifically that presenting at a symposium, even if they publish conference proceedings, does not disqualify work from being submitted for publication.  
JAMA and the New England Journal of Medicine also place an embargo on works submitted for publication.  They specifically do not want articles which are currently under review by referees to be leaked or announced to the media.  I don't think that sort of marketing hoopla is as common in mathematics.
But, in my opinion, common courtesy certainly dictates that collaboration on research implies a joint duty to decide together where to submit for publication and where to present the research.  If there are arguments about where, when, how, and how much to present of whatever you are working on, that is more about the ability to collaborate and peacefully negotiate decisions, and more of a personality matter.
