apps:// links work on the N9 browser if you install the Apps For MeeGo client from http://apps.formeego.org.
Besides giving you a client application for accessing the repository, this will also register the package repository so that you could use apt-get if you'd like, and install the necessary keys so that App For MeeGo is regarded a trusted source by the N9, and allow apps to request the same Aegis privileges as those published via Ovi store.