This I feel is one of Plato's later dialogues, though it is still very Socratic in form. It is believed that the main part of the dialogue (it is not really a dialogue in that it seems to be more like a retelling of an earlier event, an event which most likely occurred before Plato was born, than a first hand account of a discussion). However, I also note that there is no reference to the theory of Forms, so it appears that this particular work is probably more Socratic than Platonic.
As I have mentioned, the discussion (for want of a better word) is set about fifty years (or more) before the dialogue (for want of a better word) was published. At the time, Athens was at the height of her power, and the thirty year long Peloponesian War had yet to begin. A famous philosopher, named Protagoras, who was aged around 65 at the time (according to the translator of the version that I read) was visiting Athens, and one of Socrates' friends (Socrates was aged around 35 at the time, so had yet to become the Socrates that we all know and love) wanted to go and give money to this guy to become a student. Hearing this, and obviously a little disturbed about the whole thing, Socrates decides to go with his friend to meet Protagoras (Protagoras was actually quite famous at the time, so it wasn't as if some unknown had appeared in Athens and started sprouting a lot of rubbish).
One thing I found interesting was when we first meet Protagoras. The discussion between Socrates and his friend at first sounded as if his friend may have been seduced into joining some sort of cult. Basically give this guy money and he will teach you how to be a good and moral person. Remember, Socrates actually did this for free because he did not believe that one should have to pay to be taught how to be a good and moral person. This was not like learning how to argue (rhetoric), as the text suggests, but morality. Anyway, when we first meet Protagoras, we see him with a group of Athenians clustered around him listening to him intently, and a larger group of followers eagerly taging along behind (I guess they had already paid their money). To me, Protagoras really does sound like some sort of Jim Jones.
Anyway, I should actually talk about the discussion between Socrates and Protagoras, and it is the question of whether one can be taught morality. Protagoras says that yes it can, but of course he is going to take that line because he is making money out of teaching people morality. Socrates does not necessarily take the opposite view (he never does) but rather tries to poke holes in Protagoras' argument. In a sense Socrates takes the line that experience cannot be taught, and morality is something that is learnt through experience. As we interact with people we learn what upsets them and what does not upset them, and we tend to drift towards not wanting to upset them. In a way, it goes back to the basic Socratic principle of nobody does wrong willingly (which I sort of don't agree with, but if we accept that people's sense of morality is subjective as opposed to objective, then that is the case).
Now, there are some interesting things that do come out of this dialogue. Protagoras tells a story of two demi-gods, Thinxahead and Thinxtolate, who are given the takes of designing and creating life on Earth. Thinxtolate decides to take it all on himself, and hands out all of these gifts to the animals to allow them to survive, but when he gets to humanity, all of the gifts have run out, so there is nothing left for them. However, Thinxahead decides to give humanity the gift of wisdom and intelligence, and to do that, he steals it from the gods. In a way it is similar (but no where near identical to) the Genesis account where humanity is given the breath of life from God, which sets them apart from the animal kingdom.
Then there is the idea of cowardice and bravery. Socrates seems to take the position that people are cowards due to ignorance: cowardice is the fear of the unknown. People are cowards because they are ignorant of the action (and I must agree with that, because I have known cowards that are cowards because they simply accept that they can't do something because they do not believe they can do it, which is ignorance), however bravery is being able to respect what is known. I don't think Socrates meant that bravery is taking on a fully armed Spartan soldier with a straw hat, that's not brave, that's stupid. As a side note, he suggests that Spartans are wiser than the Athenians because of their ability to make piffy one liners (much like many of Arnold Swartzenegger's characters, which I would hardly call wise).
The conclusion is that there is no real conclusion (as happens with many of Plato's dialogues, because he wants us to work it out for ourselves rather than spoon feeding us). Protagoras simply says that he is sick of talking to Socrates and will continue the discussion later (but also praises Socrates on his ability to argue and says he will one day become a great philosopher, no doubt something added by Plato), and Socrates simply says that it is getting late, he has things that he has to do, and pretty much goes home.