Last night the announcement was made at work that I am no longer (birthname) "she", but now Jamison "he". I am happy to say that management handled it really, really well, and so far it's been a positive experience. Whew!
When the announcement was first made it was a little unnerving, as it was met with utter silence. You really could have heard a pin drop. Then the head honcho and the head of Operations at our DC each made short speeches about their admiration for the atmosphere of acceptance they have encountered at our facility, and the company's feelings about diversity, and offered me public congrats. The head of HR also stuck around for a couple hours that night, even though she usually works days, so that she would be available to answer people's questions and to head off any issues that might arise before they became major problems. So, basically, it was handled in a very positive, "we know you'll all do the right thing and be respectful" kind of way, and people seem to be following the example.
It's only been one night, but so far nobody has had an issue with me. Several people offered me their congratulations. One person said she had thought something was going on, but had been afraid to ask.

Interestingly enough one of the people that I was most worried about having an issue with it was actually one of the first to say congratulations, and to sincerely offer the opinion that he admired the guts it took to go through with transition.

And one of the guys from the shipping dock was moved to tears when he expressed his admiration for my courage. That was a bit awkward, but very sweet.

(I'm putting it down to sympathy hormonal emotionalism, given his wife is 8 months pregnant.

) And a couple of the coodinators made a point of letting me know that they had my back if there were any problems. So, at this point, I'm coming to the conclusion that I work with a really great group of people.
The main question I've gotten so far (repeatedly) is, "Can we call you James/Jamie?" I find it interesting that, when I was a girl people could handle 3 syllables, but as a guy people find it too difficult.
P.S. Another cool thing - Last night was also the 2nd anniversary of my hire date. Generally the management team signs a nice little thank you card for each employee for his or her anniversary. I'm very happy to report that they each made a point of including a brief note addressed to me with my new name. I thought that was a nice touch.