Only caveat is you have to get your friends to join #groupname... you can't arbitrarily say your friend Joe is a member of both #coworkers and #friends... he has to join those groups.

That may be really obvious, but getting everyone you know to self-categorize for your convenience can be a challenge. Being able to label someone for your own purposes is much easier.

If you explicitly had that need, I feel like a mailing list could serve the same purpose. That being said, I feel like you could set up something to email-blast a group of people with your latest links from twitter for that group.

Ah, yes, that could work, too.

However, wouldn't everybody (those who I didn't tell to subscribe to my group page) following my twitter account get those tweets?

Unless you have an explicit need to hide x group's links from y group, you shouldn't have an issue. If you clearly state "here's the group link page. Use it" and they go there and they subscribe, it's all good. You don't need to control people (no! You can't follow my twitter account!) you just need to provide value (Here's my group link page, with all your shiny links).

It isn't that much that I don't people to follow my twitter account but I don't want to spam those people with tweets containing links they aren't interested in and about whom I know they won't be. :) Hence the need of groups.

I'm having a hard time seeing how using the search page (http://search.twitter.com/search?q=%23groupname) doesn't solve that issue.

Well, what about those who already _are_ my followers? Wouldn't they see each and every of those group tweets?