It's a "starz" series, I think HBO just airs it.
The story is based on historical events, but the details and intricacies they made up are pretty cool too.
Edit: http://www.youtube.com/watch?v=GObQ_VCGu6w is the trailer for Season 2, in case anyone hadn't seen it yet. Looks pretty awesome to me. I won't ruin it by saying anything yet. Watch it first.

Whenever someone says that about Spartacus (or most modern films based on ancient history for that matter) I cringe a little. The only thing it has in common with real historical events is that there was some Thracian gladiator called Spartacus who escaped and killed a whole bunch of Romans and eventually was defeated and killed along with all his people. Everything else about the show's story is completely made up.
They did definitely succeed in creating a very believable setting, life in the Roman Republic is depicted very accurately. I was especially impressed with how they depicted the relations between slaves and their owners. In Gladiator for example, you never really see how [censored] hard life for slaves could be. In Spartacus it is much more realistic. Quite shocking at times, but Roman society was very brutal.
Yeah, that's what they were intending, since they didn't know whether or not he would be able to come back. But it's okay, because GoA gave us Gannicus, and if you watched the trailer for Vengeance you'd see that he's coming back.

Gannicus was cool and all, but I was mostly interested in Oenemaius and Crixus, they are both great characters portrayed by amazing actors. And Barca is [censored] awesome.
Well it looks like http://www.nytimes.com/2011/09/12/arts/television/andy-whitfield-star-of-spartacus-series-dies-at-39.html last night because of the cancer. Terrible outcome, he was a great actor in Spartacus.
Too bad, I was still hoping to see him again in later seasons. I've heard that the new guy is pretty good though, and the supporting cast is great as well so I think the new season will be just as good as the first two.