How long would you be a temporary employee before you began looking elswhere?

I am asking because I have been a temp for a little over six months. It is not that long of a time frame to me, but the concern lies with management hiring two people full-time off the street, and looking for a third while i am still a temp. The first two, no one even knew about until they were hired and the announcement was made by the manager. this even upset full time rmployees because the positions were new, and not offered to full time employees first. The third was discovered accidentally while posting an ad on an employment site. When asked about the position I was told that is was a replacement for a woman who put in her notice.

I cant seem to get an answer about my position becoming a full time position. It began as a new position but quickly changed into an existing position due to necessity. I am not doing what I was initially hired to do, but I am flexible and willing to do whatever is asked of me. What would you do?