Our club uses a combination of wireless linking and an IRLP reflector to tie 4 sites together. Some of the members have also built their own IRLP stations at home and connect to the reflector so they can run super-low power when around the house, which is a nice feature especially if you happen to live in a bad spot and have trouble hitting a machine.
However, I'm not in favor of Internet linking. We have lots of spectrum above 70CM that most hams never even think about. That spectrum will get more and more valuable over time and if we don't make use of it, someone else will. Google for one has shown they are more than happy to petition for license free "white space" radios that will work just well enough to reach a tower run by a commercial enterprise (like... Google?) to make money without having to resolve any issues that may come up with other users. It won't take long for them to realize there's a whole bunch of open territory in our ham bands, much of which is already set up for unlicensed use on a secondary basis.
I'd like to see a migration to broadband digital radio linking, with an eye toward a "dumb pipe" network between sites that could be used for linking analog repeaters, passing APRS traffic, digital repeaters, or whatever else we can throw at it within the confines of acceptable amateur traffic. But of course that takes money and engineering, two things we never seem to have.