The first major distribution to ship both GTK+ and Qt by default?
Mandrake used to ship both, back when it was a major distribution.
So did SuSE, and I think it remains one of the big ones.
Not completely sure about Slackware, but I think it had both of them too.
I'm not certain, but I believe most Qt/KDE-centric distributions also shipped GTK+, if only for the killer apps that needed it (the GIMP, for example).
Only GTK-centric distributions could affoord to be snobs.
Ubuntu does Gnome well by all accounts, but they are not the be-all, end-all of Linux development. They have great marketing, though.