Установить redirect_to с первого URL на второй, то есть:
from django.conf.urls.defaults import patterns, url, include
from django.views.generic.simple import redirect_to
urlpatterns = patterns('',
# Example:
url(r'^$', redirect_to, {'url':'/app/'}),
url(r'^app/', include('app.urls')),
# ...
)
НТН