I think the answer to your question is largely based on two important factors: location and specialty.
From my travels as a fourth year over the past few months I have noticed that striking differences in the perceptions of DO's exist depending on where I was geographically. It seems that the midwest is very friendly and open, however, I wish the same could be said about certain parts of the northeast such as Boston. Unfortunately, a lot of the PDs at big Boston programs are still pretty old skewl and not as accepting to DO's. I realize there will be those that write in saying the opposite, however, from recently completing an elective in neurology at a very well respected, ivy, 'H'ard core program I can tell you that DO discrimination does still exist among administrators. For the most part I think that the younger and up-and-coming generation of physicans will be much more accepting and any discriminiation will very almost non-existant in the future.
Another example is of a classmate of mine who applied several months ago to do an elective at a smaller, southern low-tier program only to get a rejection flat out stating that the reason she was rejected was because she was a DO student. I don't even know if this is legal but just further illustrates the point that discrimination is still out there there but it appears to be sparse.
