After a closer look, she looks like Lily- explains her comments about borrowing her shoes earlier in the episode.
The camera followed her boots for five minutes, but we only saw her face for 5 seconds.
She's certainly a ringer for Alyson.
When Lilly and Ted were having the conversation about being in love when their finances best friend, I was half expecting Lilly to say "Well, I eventually got over you didn't I?"
But then I've been hoping that Lilly would be the wife all along.