Seems it weren't lag after all :-)
Mindflay is broken
Ghostcrawler approved.
I tested it out alot, and I can recognize all the points. I usually have around 30ms (you won't get it any lower outside Blizzard HQ), so I think I can safely say I don't have any "lag".
Not to ofcource mention all the visual bugs in Netherstorm and Mana Tombs where it flays up in the air, rather than towards the target.
I *really* hope this get fixed before WotLK raiding.