i know with my two they go in phases. my son(3) went thru this phase last summer where he would wake up every night and come down to our bed. this went on for months.
we did what i guess they would call the crying it out method with him when he was about 9 months. but..from talking to other moms i have found out that alot of people, me included at first, didn't have the correct information on how it was done.
http://www.babycenter.com/refcap/baby/babysleep/7755.html
what we did was let him cry for 5 minutes. then we'd check on him. comfort him, pat him..but not pick him up. lay him back down. say something soothing. usually after 3-4 times of this he was asleep.. but we also knew his cries and could determine the difference between cries of wanting us to come back up and cries of being scared and something wrong. those later cries we would go up and pick him up to totally comfort him. but you can modify any method of anything to your life style /personality. (we were doing it the way the book said i found out later,,,,but i thought we weren't..lol. if that makes sense)
there was a 2006 new book that Ferber wrote..it's mentioned on this link as well.
with our son we used a nightly routine that included lulliby music that we played after we left. with our daughter she has her nightly routine and we turn on her bear that plays that heart beat sound. if she wakes up,, we sooth her and turn her bear on. our son at 3 now does a good job of puting himself to sleep. but now there are 'monsters' to contend with..lol
it's funny,, when my 21 year old nephew lived with us(mom/dad) along with my sister, i can remember at nap times my mom would say watch the clock when he's crying, in 7 minutes we'll go check on him. 7 minutes feels like forever when you are listening to a child cry. but even back then, and i'm sure before, there was always a 'cry it out' method but just not called that or had as much publicity or objectors.
my heart goes out to you that she cried for 3 hours! i wouldn't let her cry that long. that's not part of the method.
Good luck!
you have to take the part of all these ideas and try them out, make them yours,,
T.