So what's the mythos behind this show? I've never read the comic and I've no clue about it other that it takes place in the future. How is superman (boy?) there in the future? On the show he doesn't even know why he's there.

IIRC,

In the cartoon they(Brainiac?) apparently brought him there. "Superman" is considered a Legendary hero in their time and they needed him. After he helped them inteh 1st ep he decided to stay because they said that they could return him to the exact time they took him and it would be like he never left. They apparently grabbed him at his "superboy" stage because he's barely learning what he can do. Hell, in the 1st ep Lightening Lad had to show him how to fly right.

I can't tell you much about the comic because although I like the cartoon, I was never a fan of the comic.

The Legion of Super-Heroes comic started in 1958, with the three members from the 30th Century meeting Superboy, who had been their inspiration, to offer him membership. As the comic went along, more members were added and Superboy worked with them more and more.

With the DC Comics "reboots" affecting time, the team's inspiration has changed from Superboy to Superman to Valor (Mon-El, later M'onel) to all heroes in the distant past. Also, the involvement of any "Superboy" character has gone up or down. Supergirl was a member for a while until she was removed from continuity during Crisis on Infinite Earths; she was replaced in the comic by Andromeda. Presently in the comic, Supergirl is a member.

The animated series uses "Superman" to avoid becoming involved with the current lawsuit over who can properly use the name "Superboy".

This cartoon is better than I thought it would be, not a must see like Justice League but still good.

Yeah it's a decent cartoon.

It was a little creepy when he was dating that girl and being called "Superman."

They also had that lame explanation back in 86 where every story that took place with Superboy was a big deception by the Timetrapper to dupe the LSH into thinking that they were really working w/ the real Superboy and not knowing there really wasn't one. I'm assuming they had fractured events in their history and thought Clark assumed the identity of Superboy before becoming Superman. It's sort of confusing now to me because an adult Superman had adventures with the LSH. How could he not have remembered his adventures with them as a teenager? It doesn't mesh with either the old timeline or the new one. Anyways, I thought it was stupid because the 1986 story occured after the fact that they destroyed all but one of the multiple earths. The writers at DC couldn't resist making another earth just to explain away the Superboy storyline and killing him off.

Haven't seen this new one (no cable), but in the Superman animated series, 3 of the characters come back to the superboy period to stop Brainiac from killing him. Don't know if they're tying it in though -- is this one supposed to be the Diniverse too or is it more like Teen Titans?

In an episode of Superman: TAS they did that one where they stop Braniac from killing Clark Kent. I do remember that.