As I have said on a number of occasions, Google often shares good information on how their search engine works. They don’t tell us quite the detail we might want, but they aren’t as secretive as some might claim.
Check out this presentation from Googler Matt Cutts:
I was interested to see this point:
The SEO community generally favours no spaces over hyphens for reasons unknown to me, but it is interesting to see that everyone’s favourite Google blogger has suggested something different.