In the NT we see that people can "desire" to become a bishop, and that is a good thing. I watched the other night as a missionary talked about the first time she wanted to be a missionary. It was a desire, and I am sure she feels a sense of calling, but does the NT speak of it? She spoke so passionately that she wanted it so bad at eight years old, and kept trying to go over and over, until finally at 28 years old, she was appointed. We now see people announcing their "calling" into the youth ministry, or being called to be a worship leader, pretty soon we will see people being "called" to be Awana workers. There are hundreds of non-profit ministries that some feel a calling to be a part of. Is our terminology, practice, and theology consistent with scripture? This is a question that we should always be asking. The reason it's important is the mindset it creates in our churches. Some might argue that this is only a terminology issue--semantics, but I think it is much more.
We live in a changing church culture, where we are discerning and sometimes separating denominational and church tradition from biblical paradigms. Sometimes this is done better than others; again, I think it is important, especially as it relates to a missional context--church planting and international work.
These are my just musings, and they need much more reflection by me and others. I look back on my own life and think about my calling. There are some questions related to it for me, but there are fewer questions in my mind about the good work, and the gifts to do that good work, which God has put in me.