There's no alternative, which is a bit of an ominous sign for both Picasa Web Albums and Aperture.
Update b: Looking at this more closely, Aperture has some interesting web journal features -- that work with MobileMe. Which was shut down last year. This keeps looking worse. (Maybe it's because I'm on Snow Leopard. I think Lion Users may see iCloud.) Incidentally, this is quite a good article on all the nasty bits of Aperture photo sharing.