Interesting question. Just some more anecdotal answers for you.
My daughter, now 4, walked at around 16 months, and was speaking just shortly afterwards.
However, my son, 23 months, walked at 10 months and was walking a soccer-ball across a room and back on the eve of his 1st birthday. But he only says no(or nope for fun), clearly. It is interesting how complex a conversation you can have with this little guy and he understands, but only verbally responds with "nope" and a smile. He does shout "da" for me, an "ah" for his sister (ah has absolutely no correlation with her name, by the way).
We taught both our kids sign-language (just for fun) and my son uses it nearly exclusively, and my daughter when she rather not speak.
We are not worried, remotely, since kids are products of their environment; and we've realized that the shade of the moon through the clouds on Wednesdays is more predictable than child developmental milestone timing.