I rely a lot on trackbacks to interact with the blogs I deal with. Obviously within wordpress the trackbacking works superbly. I also have no problem with trackbacking with blogger.
But 95% of the time, trackbacks to powerblogs or typepad simply don't work.
I encourage wordpress brass to fix this. If we are able to trackback to the big boys, then we get more traffic. More traffic for us means more money for you (I think).