But before Dirty gets in here and preaches his holy words. Let me take a crack at it.
"There is small group of grizzed vets who play on ICO. Why dont you join us? Peak game time is around 7-9 EDT. Usually 5vs5 random map, fastest settings all around."
Not bad, but the peak time now seems to be 2-11 pm U.S. Eastern Time. (Carbon, why don't you getcher butt onto ICO? There are still newish players around for you to go up against.)
Sadly, for numerous reasons, many of which are historical, Sins has low online player counts. When I say low, I mean only 30-40 people online (for the Diplomacy expansion) on a weeknight. A couple hundred people have played the game competitively in the past, but many have moved on. Some are coming back now in anticipation of the upcoming Rebellion expansion. Now for the good news--this game rocks and it's an overlooked gem, and there are a couple 4v4 and 5v5 games every day, but you have to wait for them to fill. There's more activity on the weekends.
With such a small player base it's hard to have much of a competitive scene, and although a few clans formed, the game never really had enough players to support leagues or ladders. For some reason Sins just never sold well to the online multiplayer RTS crowd. However, you can still have a lot of fun playing in 5v5 games. Many of the people who play are pros, grizzled vets who will provide you with a tremendous challenge and stomp you while you get up to speed. There are even pros-only games sometimes. So, if you're asking whether there are competitive games to be played, the answer is yes, but they don't count for anything other than for enjoyment and ego gratification. We even have a system set up for the 4v4 and 5v5 games where two captains draft-pick the other 8 players.
You should know that the upcoming Rebellion expansion (late 2011 or early 2012) will be a stand-alone product, meaning that you don't need to have bought any previous Sins games to play it but it will include all of the content of the earlier games. So, in a way it's like it will be a Sins-2. Hopefully Rebellion will bring hundreds of new players onto the server now that the online multiplayer aspects are more polished (less lag, fewer game crashes and desyncs, etc.--problems that plagued it in the past). If you're serious about the game, try the demo. If you think you'd like it, consider finding a sale on the Trinity pack (the original game and both expansions) and that will save you $10 on the Rebellion download. This way you'll have a couple months to get up to speed before Rebellion hits.
As I type this, there are 38 people logged onto the Diplomacy expansion server and it's 2:00 am U.S. EST. Do note that the Vanilla/Entrenchment server is pretty dead and just consists of friends playing comp stomps.