I apply for a few places and got two reply so far.

A prospective supervisor said he will serious consider my application;
Another said something like: "there is an attractive possibility of winning a XXX scholarship if you......".

Should I be optimistic about this or they just being polite? Since one of them also writes my reference and will know every place I applying for, I don't want to show an impression of lacking commitment by applying too much universities if he really think I have quite a chance.

I can't see why they wouldn't be honest with you regarding the chances of your application. In terms of applying to other places, of course you should so that you don't pin all your hopes on one position. I've read from some people on here to apply to as many places as possible. I disagree because there's no point writing dozens of poor applications. Instead, write say, between 5 and 8 very good proposals and tell you're prospective supervisor that you're doing this (but emphasise that it's his project that you really want to do). It shows you're committed to doing a PhD and that you're covering all bases. It's a perfectly reasonable and sensible position to take. If you tell them you're not applying anywhere else they probably won't believe you anyway!

apply to as many as you can. i dont doubt that they mean it but you have to be prepared for other applicants that may contact them also so dont pin all your hopes in one place. they wont mind either if you do.

I agree, I dont want to dash your hopes or anything, but I am currently searching for a PhD and saw one last year, I met with the supervisor and everything, then he contacted me saying, how suitable he thought I was, and how he and his collegues felt I would greatly contribute to their team. But unfortunately he then phoned me about a week later and told me he was sorry but he had met with someone else he was going to offer the place to. So I'd definately keep your options open if I was you

what an amazing story, son of a (..).

I really think that this professor has bad manners and is an arse. He let you believe for one week that you got the phD position and then he just let you down==unbelievable.

That does sound incredibly harsh. I've heard a couple of other people have that happen to them, as well...

Yes, that's just irresponsible. But on the other hand you also avoided a not very reliable supervisor who might ruin your PhD or even your career otherwise. At least I would not be very fency to work with this kind of supervisor if I have other choices. Better find out this earlier than it is too late.

Anyway, thanks a lot for all the great advices. I was told that they will give me the answer next week. So for now I can only wish for the best, and prepare for the worst.

I think you should tell us the name of this professor- for two reasons:

a) it might prevent prospective students to apply for his supervision

and more importantly

b) I think he deserves a little bit of "public ashaming" for his action

Yes ULUG, I totally agree with you. There r lots of bad pple everywhere....