I'd have to agree with MJ and Rashmi about relationships being defined by the individuals involved.
In my personal experience, every gay male I've encountered so far has fallen one of these five categories:
1. Guys who elicit a strong emotional response because of their sensitivity/goodness -I can't be 'just friends' with this group, because my feelings for them run deep and I get emotionally invested in them.
2. Guys who elicit a strong intellectual response because of they're on the same wavelength as me -again, I can't be 'just friends' with this group either, because their intellect draws me out and I start falling for them.
3. Guys who elicit a strong physical response because of their looks -it's difficult to be 'just friends' when I've got a raging hard on the whole time I'm with them. lol
4. Guys who are a combination of two or more of the above -Irresistible!! No way I can be 'just friends' with this group!
5. Homosexual men who neither arouse my emotions, nor mental faculties, nor basal desires -yea, I guess I could be 'just friends' with this group, but honestly, I'd probably just feel too disinterested to even bother with friendship.
So I guess my answer would be no, I can't truly be 'just friends' with a fellow homo regardless of whatever act I might put on the outside. ;)