Wispy British actress Sienna Miller is heading to Broadway next season to star in Patrick (Closer) Marber's After Miss Julie. She joins an increasingly steady stream of movie types heading to the stage. What gives?

Among the recent ranks of mostly-untested LA fugitives are Jason Biggs, Jennifer Garner, Katie Holmes, the mercury-doomed Jeremy Piven, and the soon-to-be-hoofing-it Lauren Graham, Susan Sarandon, Rupert Everett, and Jane Fonda (among others). While big namers do earn more than a typical theatre star would to glow under the lights, the pay isn't great and the performance schedule can prove grueling. So why are so many folks jumping on the theatre bandwagon?

Well, of course there's the whole building-cred thing. Though that's sort of been debunked in years past. Ashley Judd (Cat on a Hot Tin Roof) and Julia Roberts (Three Days of Rain) proved that bad notices for stage work can make you look like kind of a jackass. (See Julia's sad "you people are insanely talented" Tonys mea culpa.) And how often has the risk really paid off? Holmes (All My Sons) and Garner (Cyrano) got mostly decent reviews for their performances, but does anyone really respect them more because of it? At some point—especially in Ms. Holmes' case—doesn't it start to seem like it's just a lame fallback? When the screen work dries up, go hobbling off to New York where devoted theatre fabs will greet you with open, grateful arms. Right? Increasingly, not so much.

Did you hear that collective grumble that rose up among young male actors in New York when Haley frickin' Joel Osment got cast in the ill-fated revival of David Mamet's American Buffalo? The kid got that role simply because he starred in a couple of shitty movies ten years ago. He'd done little to no acting since. But producers, desperate for ticket sales, will throw just about any known screen actor into a significant role in a play, despite their lack of any discernible chops. Which is, you know, kind of a slap in the face to actual "theatre people." The more it happens, the more true straddlers of both mediums—your Mary Louise Parkers, your Laura Linneys, your Ethan Hawkes—get lumped in with the sad pile. The stunt casting cheapens the medium, reducing it to just an excuse to see your favorite star live and saying things. (Who the hell really wanted to see Pygmalion? No, they just wanted to see Angela Chase up close.)

So who knows about Miller. She did study acting in New York, but so did Jessica Alba. Maybe she'll flourish though, and stick around. Just once it'd be nice to see that conversion (you'd better stay put, Denis O'Hare) happen in reverse.

Anyway, this is probably just sad theatre nerd grumbling—there are plenty of good, hardworking theatre actors all over the country (Elizabeth Marvel, Thomas Derrah, etc.) who've seemingly no motivation to cross over into the glitz. It's just sad to see them overshadowed. But really, who's to argue with ticket sales? Lord knows the industry needs it.

Let's just avoid that Anne Hathaway Oleanna that was rumored about a while back. I don't give a shit if theatre is her "first love."