I am the developer maintainer of AV Linux which has featured Kdenlive in the last few releases, I am working on an upcoming release and have upgraded to the latest 0.7.6. I am noticing very ugly font rendering in the menu areas, however the font rendering is fine in the smaller tab areas. AV Linux uses LXDE and changing the font settings within LXDE won't do anything to KDE4 apps. The fonts were rendered perfectly well in version 0.7.5.
I should also mention that I've pored pretty deeply into /usr/share/kde4 and all the various .rc and .xml files but haven't seen anything relating to fonts yet.
I realize Kdenlive is a KDE4 app even though it will run on other D.E's... can anything be done about this without installing KDE4? LXDE is fitting the bill very nicely for everything else so moving AV Linux to KDE4 is not an option. I value Kdenlive as an application and wish to continue to promote it within AV Linux.
Great job on development BTW!