In yesterday's video from Google's Matt Cutts, Matt addressed a pretty straight forward question we've touched on here a few times about how to inform Google of multiple ccTLDs for your business.
The real answer is to use a href lang and that is the best approach.
But Matt gets into linking between your ccTLDs. Here are some points on that:
(1) It is okay to link to all your ccTLDs but don't over do it in the footer.
(2) At max link to only 4 or 5 ccTLDs in your footer
(3) It's best to set up a country landing page and link to them that way on that page.
Now, where it is not okay or you should be considered about linking country sites together is when you are not going the ccTLD approach. So if you have bluewidgetsincanada.com and bluewidgetsinsweden.com and bluewidgetsinaustralia.com and so on. When you go that approach, Matt says be careful and probably do not link to all of them like that.
He gets to that point about 3 minutes and 20 seconds in. Watch it yourself, here is the video.
