tewmonkey, cardiff,wales: Until recentley (the last six months or so) a high ranking was achievable by submitting articles to article directories (providing they were 40%-60% unique),  it no longer seems to be the case.  Have links from article sites been de-valued at all?

Matt Cutts: In my experience, not every article directory site is high-quality. Sometimes you see a ton of articles copied all over the place, and it's hard to even find original content on the site. The user experience for a lot of those article directory sites can be pretty bad too. So you'd see users landing on those sorts of pages have a bad experience. 

If you're thinking of boosting your reputation and getting to be well-known, I might not start as the very first thing with an article directory. Sometimes it's nice to get to be known a little better before jumping in and submitting a ton of articles as the first thing.

Anonymous: Sitemaps question: If my website has an extremely large number of pages, like Amazon.com, should I include every single URL that I want indexed in my XML sitemap?  If not, how should I go about populating my XML sitemap?

Wysz: Feel free to use your Sitemap to list all of your pages... that's what it's for! :) However, if you have many duplicate URLs for the same content, then you may want to only list your preferred versions of the URLs in your Sitemap.

Scott, Minnetonka: Do inbound links from other sites owned by the same company help or hurt rank?

Matt Cutts: I find that inbound links from the same company tend to break down into two camps. You'll find mom/pops that have a very few sites in one camp, and that can make sense if those sites are linked; in the other camp, I've see SEOs have 1000 or 2000 different domains and cross-link them. I definitely would not recommend that.

I think a lot of the litmus test in my mind is whether it makes sense to a regular person for those domains to be interlinked. If you look at a product like Coke, people aren't surprised to see that they have coca-cola.co.nz and several other domains. If you go to coke.com, it's perfectly reasonable to ask users which country they're coming from, and then send them to one of a bunch of domains. But if a regular user lands on example.com and finds 20 or 30 cross-links at the bottom of the page and they look like off-topic or cookie-cutter or spammy domains, that's going to look bad to almost anyone.

Maile Ohye: Hey Scott, I'm not trying to give you the run around, but this is a bit situation specific... overall, though, I wouldn't look at these links as helping or hurting your rank when written in a helpful manner to the user.

So, if you run a sporting goods site, and you link to your sister companies for camping and tailgating equipment, that's good for the user. More happy users can lead to more buzz, leading to better rankings.

If your sister companies are just linked at the footer of the page, in hopes of cross-advertising or getting more links, it's not likely to add value to ranking or the user. In extreme cases, if it's a bad neighborhood, these links will certainly not help you.

Put yourself in the user's seat, and do what makes sense for these links. Good luck!

Rick Rayn, Indiana: What weight does the age of a site and the amount of time a domain is registered for have on it's search placement?

Matt Cutts: In the majority of cases, it actually doesn't matter--we want to return the best information, not just the oldest information. Especially if you're a mom/pop site, we try to find ways to rank your site even if your site is newer or doesn't have many links. I think it is fair for Google to use that as a signal in some circumstances, and I try never to rule a signal out completely, but I wouldn't obsess about it.