Rebecca reliably says 'mumumumumum' for her Baby Mum-mums now. She also says gogogogogogur for yogurt.
That makes it 4 words with mamamamamama and dadaaaaaa which she says frequently.
She also leads people to her high chair when she's hungry and pulls her blanket through the bars of her crib and starts sucking on it when she's tired.
Quite the little communicator. It's amazing. :)