Advice for early grad student: how to professionally present tentative research idea(s) before one has chosen a topic I'm a 2nd-year grad student in a US PhD program in one of the social sciences. Coursework has forced me throw out the initial ideas I had about research, which I proposed in my application nearly two years ago. Now I'm actively hunting for the "right" topic. 

People ask me all the time, "what's your research on?" and I'm not sure how to answer.

This is not about "how to pick a research topic" as much as how to professionally present one's very tentative research idea(s) before one has a topic.

Should I:
1) Preface any response to the question with "I'm still early in my program and haven't written my dissertation prospectus yet, but I'll probably focus on ..."
2) Should I be honest about having multiple ideas or just pick one in order to better focus the conversation? 

Any advice probably differs across contexts -- i.e. talking with peer, talking with senior scholar. All tips are appreciated!

I know this question is subjective, but I think about the situation every day, and I feel like I need some advice.
You should be honest for sure. If you don't know something, do not pretend you do because you may face a person who really knows what you try to talk about and then, if you have only a superficial grasp of the subject, you are toast. Just say straight that you've heard that X is an interesting subject, that you have already read , that you want to learn more about it and, perhaps, try a research project in that particular area, and that you have this and that idea and wonder what can be made of them. That will get you the warmest response you can expect from the person you are talking to ("the warmest" doesn't mean "warm", by the way) and you may get some good advice or help this way from a "complete stranger". 

I admit that many people fail to understand that knowing and openly delineating the limits of one's knowledge and powers is "a professional behavior". Nevertheless, those whose respect you should really earn during your academic career (whether they are your professors or your fellow students at the current moment) will judge you from this standpoint. The opinions of the rest may make a lot of difference on the short run but none on the long one.