The shrek movies are set in a suedo-meadival times,how would they fit into ars magica?
The movies would not fit at all- no projection equipment, no electricity, and no movie theaters.
The world-concept would fit much like certain medical apparatus I can think of- technically right for the orifice in question, but hardly comfortable or attractive to the majority of the population. But hey, what folk do in the privacy of their own gaming room is none of my concern... 
There is no wrong way of gaming, but not every way is right for everyone.
a bit tightly about the waist methinks
lolololololol 
I do not think the Shrek moves are good inspiration for Ars Magica. Shrek base itself on using popular faerie tales and mixing them up and making something new. Ars Magica base itself on a world that is the way pepole of the middle ages believed it to be, there is a big difference. Not that it is anything wrong whit Shrek, I have seen Shrek 2 several times and think the movies are grate fun. However they do not resemble Ars Magica in any way. If one want movies as Inspiration for ARS i would recommend movies like Kingdom of Heaven, Mists of Avalon, King's Knight and a few others like that.
King's Knight? Don't see any IMDB listing for such a film. Are you perhaps referring to the Arthurian takeoff "First Knight" (with Connery and Gere)?
That might be it. I hate it when they re name movies when they bring them to Norway. It create a guess work of what the English title is. But yes that it the one, sorry for the mix up.
I think the movie Merlin with Sam Neill is as much like an Ars setting as I have seen in a film (despite certain comedic elements) what with the inclusion of the fae and the stuggle between dying paganism and burgeoning Dominion control. Mists of Avalon does come close though, especially with the representation of Avalon as a hidden regio.
Heh, I remember that "Young Frankenstein" was renamed "Frankenstein Junior"- not quite the same feeling, somehow.
This thread reminds me, on a couple levels, of an on-line discussion once about the Robin Hood stories, and it took several exchanges before it became evident that some posters' entire knowledge of Robin Hood was from the animated Disney version of same (with RH as a fox character, Little John as the bear, the Sherrif as a snake, etc etc).
Just because a movie or book draws from the medieval period does not give them all the same flavour. Despite the superficial similarities, Shrek has little in common with Disney's animated classic Cinderella as far as feeling or atmosphere, the latter being perfectly appropriate, imo, for Ars. A wicked (hedge) witch serving as court magician to a diabolist queen? A band of faerie earth-gnomes, a beautiful princess under a curse, and all the rest? Sign me up!
Now, while the atmosphere of Shrek is, imo, too light and fluffy for Ars, there are themes that could be translated. A powerful Lord (with or without the Napoleon complex) who seeks to exterminate all fae in his lands? The fae coming to the magi for help? (Or moving into the magi's lands as refugees!) A princess under a curse, and/or kidnapped/blackmailed to marry aforementioned Lord? Those could be a plothook that could go somewhere.
that is what I was going for.