Hi, I hope someone with more knowledge than me can answer these questions! I have a couple of domains doing nothing at the moment, both have quite a few backlinks and some PR. My question is - if I set up 301 redirects on both domain1.com and domain2.com, both pointing at mymainsite.com, would google then treat these two domains' backlinks as backlinks for mymainsite.com, thereby improving my SERP? Similarly, would domain1.com and domain2.com's PR be passed to mymainsite.com, increasing the PR of my main site? Thanks in advance for any answers!
Regarding PR, I hear people saying that most but not all of the link juice is passed on to the receiving domain. Remember to redirect any indexed subfolders and subpages as well.
You may watch Matt Cutt's video on the link below. Matt discusses 301 vs canonical links. http://www.mattcutts.com/blog/rel-canonical-html-head/
301 redirect not counting backlinks in google eyes, because the real page is no content, just few the source code, that how google read the web and counting the backlinks
I agree 301 redirection is not considered by Google as backlink. But I have an experience. I have 5 sites 301ed to domain.com. They are from different ip. It does improve serp. Then I moved those 5 sites to the same server with domain.com, serp decreased. I think somehow it affects serp. I don't know about pr.