I just ran across a blog written by a family practice resident, pontificating "What's in a name?" I find this to be an interesting topic, as I have struggled with it myself in the past.
This, I feel, is very generational, as well as regional. ie: I am much more comfortable calling my colleagues by their first name when they are close to my age (by which I mean within 20 years). However, my soon to be partner is 73, and although I call him by his first name in private conversation with my guy (always preceded by a pause and followed by a giggle), you can bet I call him Dr when speaking to him. (He, by the way, calls me everything from "gorgeous" to "sweets..." although generally, he calls me by my first name. In case you wonder, I don't mind--his demeanor is such that it completely does not sound crass or degrading.) I also have a neurologist friend who is about 3 years shy of being my parents' age. When he asked me to call him by his first name, it took a while (and several slip ups) to get used to.
As for regional: I did my med school clinicals all over the states, followed by residency/ fellowship in the East. I can tell you that in the midwest, it is much more common for Drs to introduce themselves by their first name to other healthcare professionals. It is understood that they, in turn, will be introduced as "Dr" to patients. As soon as I came to the East Coast, it was Drs all around. This makes me often feel pretentious, so I will frequently introduce myself by my first and last name, followed by my specialty. I let them decide what to call me. And, for the most part, I will eventually correct them to call me by my first name in private.
As for patients, I am not too interested in being buddies, so I introduce myself as Dr. Older patients appreciate the formality, for the most part. Although, I have had elderly patients insisting on knowing my first name--and then calling me by that name--which made me feel a little like I was talking to my grandparents. Also, being young and attractive, I have been hit on by patients (of all ages), and I believe that introducing myself as "Dr" nips that possibility in the bud--sometimes. On the other hand, introducing myself as my first name invites that kind of discussion.
Of course, things will be a little different very soon. I think that at my new position, I may introduce myself to patients as first and last name, and let them choose... or maybe the first name will suffice. Cancer is a place where it's nice to have a buddy.