Should you stay friends with an ex - part 2

Back in February I asked the question - should you stay friends with an ex.
At the time I didn't have the answer but I can now reveal that it can be done!
Myself and my ex are still good friends and have recently got back from Download festival.
To be honest not a lot has changed in terms of our relationship - we have just taken away the boy and girl aspect and kept the friend part.
I do have to admit though it is a weird feeling to think that I have seen him naked - I can honestly say I don't look at any of my other friends and think that.
The good part of it is is that we don't pretend that we don't have a history and he doesn't pretend that he doesn't have a girlfriend.
He doesn't talk about all the time or anything like that but I asked him right from the beginning to not act like he is not with her.
And I also wanted to make sure she would be comfortable with us being friends before I let him back into my life.
So I think the key to staying friends with an ex is to just be as honest and up front as you can and to make sure that everyone involved is comfortable with the situation.