I sleep trained my son at 5 months using the techniques of "The Baby Whisperer".
We didn't do the full on CIO Ferber method, but we did allow fussing. If he would start to really cry, we would soothe him without picking him up. If patting his back, talking softly, giving the paci, wouldn't calm him down, we picked him up. As soon as Cody stopped crying, it was right back to the crib.
It took 5 nights and he was going to sleep on his own, somewhere between 7:30 and 8. We do a bath every other night, but he knows that a bath is a bedtime cue. We change him into pjs, brush his gums (no teeth yet). Then its a bottle and bed.
One thing that made a HUGE different is we got Cody a little blanky (its about 4"x4", velour on one side, fleece on the other). He needs that blanky to get to sleep, which is good because its portable and helps him to sleep no matter where he is.
Once we got the going to bed thing down, we set a time-limit on the nighttime feed. If Cody wakes before 5:30, he doesn't get a bottle (unless he's crying and won't go back to sleep after 30 minutes of soothing). If its after 5:30, Cody gets a bottle, then goes back to sleep until 9 or 10 (except on days I work).
Night time is only one part of the sleep training. Naps are also important. A baby that is overtired doesn't sleep well. As soon as I see a sign of being tired, Cody goes into his crib. He generally naps after being awake for 2 hours. His morning nap is 1 - 1 1/2 hrs; afternoon is 2 1/2 - 3 hrs; and sometimes in the early evening (5ish) he takes another 30-45 mins nap.