I think it will be quite smart if a Ubuntu user installs a KDE/Qt application could be automatically themed to match the human (or whatever thing being used). This could be done with QGtkStyle (
http://labs.trolltech.com/blogs/2008/05/13/introducing-qgtkstyle/ ).
This, in my humble opinion, would get rid of some integration problems between GNOME and KDE applications (aesthetically) , it will make the user experience less confusing and more consistent.
Just look:
http://chaos.troll.no/~jbache/human.png
http://arstechnica.com/journals/linux.media/gtkqt1.png
http://chaos.troll.no/~jbache/qt4.png
Thanks in advance for your attention.
-Just to clarify (since I can't believe somebody can rate this down...), I meant that KDE/Qt applications installed under Ubuntu (read: Using GNOME as their desktop manager) should get this, I'm not, by any way, trying to say that Kubuntu should use this as their default theme-
-More clarification, it can match whatever gtk theme used, since it's actually rendering it with gtk, it isn't the old implementation in any way, it's completely unrelated-
PS: The tittle has a little misspelling, application should be plural, sorry for that.