I feel for you! My now four year old stayed up every night until 10 PM until he was 3. It's not as bad as your situation, but it was still very frustrating, especially because I stayed with him until the moment he fell asleep. I felt I had no control over my evenings, and by the time he went to bed, I felt frustrated and exhausted.
Everything changed when I learned to "sleep train" his younger brother, mainly based on the advice of "Healthy Sleep Habits, Happy Baby", as mentioned below, as well as techniques from Super Nanny. I realized that I could "train" my older son as well, and I did!
It was life changing! Now it's up to me, not them, when bedtime is. I do have a fairly consistent routine (dinner, bath, story time), so they are not surprised by anything. But again, the key is, I decide when to do this. When I tuck them in, whether they are ready or not, they are in bed, and I am free! And usually they are ready, because they are not overtired. Sometimes they will lay there or play for a while, but as long as I don't have to be there, it's okay with me.
Yes, getting over the hump, which involves letting the little one cry in their bed, is tough. Watch the video clip on the Super Nanny website, and you'll get the idea of how to overcome this. When I watched that clip on sleep training, I cried, because it reminded me of how life changing it was to get control over this situation.
Good luck, and let us know how it goes!