I think they big thing they look for at 1 year is repetition of sounds -- mama, dada, baba, gaga, etc. -- not necessarily with any meaning.
At 18 months, there's a wide range of "normal" -- I think anything from 5-30 words, or something like that.
By 2 years, it should be 50+ I believe, and starting to put two words together -- dog woof, me up, there tree, etc.
at 9:30 AM on Jan. 31, 2011