Alicia Silverstone joins How I Met Your Mother

...and it looks like she IS MOTHER! Ausiello reports:

Sources are confirming to me exclusively that the lovely and talented Alicia Silverstone has been cast in a multi-episode arc.
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Her character, a doctor, will be a love interest for Ted and she'll be sticking around for several episodes.
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HIMYM has yet to be renewed for a fourth season and producers have promised that we'll meet Mother before the show concludes.
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Even if HIMYM does come back next season — and, let's be real, CBS would be insane to cancel it — where is it written that Mother has to be introduced at the very end of the series?
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Alicia's the mommy!

Ah, love her. Love the idea!