Rachel Bilson and Tim Gunn sign on for 100th 'How I Met Your Mother' episode

Could Rachel Bilson be the mother of Ted Mosby's future children?

The actress, best known for her portrayal of Summer Roberts on "The O.C." has been cast in the 100th episode of "How I Met Your Mother," sparking debate over whether she may or may not be the famed mother. Fans of the series may find this song-and-dance to be familiar, as previous guest stars Sarah Chalke and Jamie-Lynn Sigler provoked similar discussion.

Bilson will be playing a love interest to Mosby (Josh Radnor). Though Bilson's reps have confirmed the news, they won't offer much information on her role except to say that as of now, the character is not recurring. 

She'll be joined by "Project Runway" mentor Tim Gunn. Chicago Tribune's Maureen Ryan reports that Gunn will guest star as a "personal tailor/ fashion consultant as Barney tries to fix a major league "suit catastrophe" according to series co-creator Craig Thomas. "Tim is basically like Barney's ER physician for a serious suit emergency."

Thomas and "Mother" co-creator Carter Bays have previously said that the 100th episode will bring Ted closer to meeting the mother than he's ever been before. "How I Met Your Mother" is famous for its fake-outs, so we'll all have to wait and see.

It seems that there's a lot in store for the centennial episode -- in addition to Bilson's appearance, fans can expect a much-anticipated musical number from the multitalented Neil Patrick Harris.

Thoughts? Sound off in the comments below about whether you think the "O.C." alum might be the one Ted's been searching for, and if the casting of Gunn is a good thing.

-- Carina MacKenzie (follow me on Twitter @cadlymack)

Comments

[Mira]

As long as they make this episode fantastic, I will forgive them for the awful, sitcom-y dribble that was last night's episode. Just because you're on the same night as Emmy winner Jon Cryer, doesn't mean you should emulate his crappy show.

[Laura]

A musical number from NPH? I'M THERE. Bilson's casting doesn't do much for me, but Tim Gunn will no doubt be fah-bulous.

[Cara]

Yay for musical number for NPH - that alone makes it worth watching! As for Bilson being the mother, I doubt it very much. They said "closer" to meeting her, which gives them a get-out. I don't think they're going to go there, it's much more interesting for them to keep teasing the audience!

[Tatiana]

Tim Gunn guest starring on the 100th episode is like icing on the cake! How fantastic. I can't wait to see the episode!

[monica]

I'm so excited! I love Rachel, and I love HIMYM. What a perfect combination.

[Kelly]

I doubt Rachel Bilson will turn out to be the mother but I'll be curious to see who they've got her playing, regardless. And that is a pretty damned awesome role for Tim Gunn.

[Elana]

Tim Gunn will so 'make it work!' As for Rachel Bilson, I think she COULD be mother-like, but won't end up being the mother in the end.