In most cases, you have the right to take pictures of people in places that are open to the public. Some venues like commercial stores, museums, government buildings or military facilities do have restrictions.

On the other hand, people who are attending these public gatherings also have rights. Some people can make objections against you taking photographs of subjects or circumstances that are sensitive to them. Taking pictures of children is one of those sensitive matters, especially for the parents. In these cases, common sense and some reservation is the best way to deal with that.

About posting those images on the web... look at it this way. The fact that you post these images for everyone to see can be seen as proof that you have nothing to hide, that you are confident that you're doing nothing wrong or illegal, and that you are reliable and responsible as a photographer. Stand your ground, be open and confident about what you're doing, and people will not only tolerate, but also respect you for what you're doing. Most of them, most of the time anyway... ;o))

Just my opinion, of course.

We do not see things as they are. ǝɹɐ ǝʍ sɐ sƃuıɥʇ ǝǝs ǝʍ