Bob Early (Philly) gave a nice clinic on this subject at the 2006 ITG Conference at Rowan University. There is a brief review of it here -
http://www.trumpetguild.org/2006conference/wed/214.html.
He gave some wonderful examples of the differences between playing second in the orchestra next to Frank Kadarabek, David Bilger, and Jeff Curnow. All great trumpet players. The same orchestra. But, oh so different. It was very enjoyable and educational.
Bob spoke mostly from the context of what it takes to play full time 2nd trumpet. Another very interesting area that I would like to hear some comments on is switching parts from gig to gig as many of us "part-timers" do.
For example, I have a gig on Sunday playing lead in a big band where we'll be doing a Maynard tribute. At the close of the gig, I've got a one hour drive to clear my mind to play second trumpet in a rehearsal with a local orchestra. That's a real head game for me and I'm glad that I don't have to do it every day.
pat