Forum posts are in Recent changes and Wiki Activity. You can filter in RC for "Board Thread", and that'll show the most recent Forum activity. (There's a little messaging bug right now that makes it say "Sesame Street's wall" rather than "the Sesame Street board" -- we're fixing that.)
On the Forum index page, there's a "Forum Activity" box on the right rail, which shows the latest posts, and then you can also drill down through the index and board pages to see the latest in those boards.
Does that help, or were you asking about something else?
Right now, you can filter the Forum activity in Recent Changes by using the namespace filter at the top -- you can check Board Thread on the list, and just see the Forum conversations. That's a bit manual; we don't have a one-click way to access it. You think we need one? It's possible; I'm just not sure where to put it.
I think the URL was dropped when we created the new filter. The advantage of the new filter is that you can include or exclude more than one thing at a time -- for example, if you want to see (or filter out) all the conversation namespaces, then that's possible now. The disadvantage is that that makes it a more complex interaction, so it's harder to use a simpler URL structure for it.
But -- it's good to know the request for a Forum Activity stream. We're getting close to a release to Wikia Labs next week, which is a nice milestone, but there's still going to be more work to do on the feature to really finish it. I'm putting together the list of things that we need to build, so that request is super helpful. Thanks!
The next step towards that happens in a week. :) We're troubleshooting it today. It's not a full-on switch -- talk pages and the new thing will coexist for a little while -- but I'm very optimistic about the progress.