It is very possible if the woman is very aroused and their lover knows what they are doing. It usually comes with a clitoral and vaginal orgasm at the same time and has to be an intense orgasm for it to happen. There is a gland that produces this fluid at a rate of one cup per 15 minutes when really aroused. It is suggested that one should go to the washroom before sex and they need to be really relaxed in order to do it or they may panic and stop the flow. It can squirt very far, I've heard tales of woman being able to hit the ceiling of all things, or it can flow like a river. It all depends on the woman, but very few women will every experience such a thing. Actually I've found out that very few women actually experience an orgasm, never mind a clitoral orgasm.
Here is a site with a lot of information about the female body.
http://www.the-clitoris.com/f_html/fr_index.htmjaa ne
Kat