A report released by Forrester last week suggests that podcasting is not only more than a fad, it’s just the first stage in what will evolve into a world of full-blown multimedia subscription. While some may argue that podcasting will never catch on, the BBC apparently has got the religion. One of the first mainstream media outlets to make its audio content available as podcasts, the BBC is now offering an RSS subscription to one of its TV sitcoms, “The Mighty Boosh.” Techdirt, which reported on the BBC’s offering, calls it a “broadcatch.” (One hopes this word doesn’t catch on as “podcast” did.) The Internet debut of the sitcom will precede the TV premiere by a week.