Roxy's been in her crate since we got her, almost two weeks ago. The first week was the hardest, but now she is accustomed to it and its her "bed". I started out by putting all of her toys in there and I bought her special treats that she only gets when she goes in her crate.
She whinned a little at first, but we ignored her and she settled down pretty quick.
Once she got used to being in her crate we'd bump up the time and then start leaving the room for short periods of time. Nighttime was the hardest. She is still very young and the first night she was up every hour... then two hours.. now she sleeps for about 5 hrs.
Now a little over a week later, she goes in her crate w/out a fuss. I put her in for nap time in the afternoon so I can have my house back and while Im cooking and eatting dinner. Then for bedtime. I will also use it occationally for time outs. I try not to associate it w/ a punishment, just when I need her out from under me for a little while.
I hope that helps some. I did a search for crate training online and came up w/ a LOT of really good info