I'm in the middle of analysing data, so I can't talk long. Just wanted to mention that 2008 has been designated the International Year of Languages by the UN General Assembly.
If I were to talk about this, I hope I would say something like what This Humanist says.
I'll also take this opportunity to explicitly list all of the linguistics-related blogs I now know of (let me know if I'm missing any):
Part of me is tempted to point out that linguistics is not immune to anti-science creationist foolishness. Another part of me is delighted that language origins are interesting enough that even pre-scientific and anti-scientific thinkers want in on the action.
And another part of me want to use this link-heavy excuse for a lazy post to point you to more reliable sources of information on how languages actually change and diversify. It's a fascinating process, in many ways analogous to species change (and in many ways not analogous). I wonder if demonstrating the observed, documented "speciation" of languages as a result of cumulative "micro-evolutionary" steps would help some of the more honestly-deluded creationists accept the parallel phenomena in biological evolution?
Here's one last link for today - food for thought for those of us who are tempted to react viscerally instead of rationally when we encounter language change in our own community.