I have heard that when domain ownership changes, the domain loses its page rank. My theory on this is: Lots of sites selling high PR domains actually cheat. They invest in high PR links for the ...
I've heard that registering a domain name for a very long time, say 5 to 10+ years, can help with your search rank. This seems at least plausible to me, since a fly-by-night, massive domain name farm ...