Did you find any good advice on this topic? I am in pretty much the same situation at the moment and am looking for examples or case studies.
Here's my opinion but it's no more than that.
G seems to concentrate on the main site as far as the SERPS are concerned, they really don't have a SERPS for mobiles. There are a few grey areas though, the SERPS do seem to differ when they relate to a geographic term.
There is a big "but" though. Even though there really isn't any different SERPS for mobiles at the moment who's to say that might not change tomorrow. So I would design your mobile version of the site as a stand alone entity which can stand up in the SERPS all by itself. More future-proof.
About the separate mobile and desktop. We made m. subdomain. WWW was penguin penalized, m. got the same penality, but m. had no links.
About internal linking. Our www has also quite complex linking structure. Separate categories, search, brands etc. Google likes it and these pages drives traffic. But in mobile version we have only /search/ link which acts as brand, category, search options. Navigation is simple and google likes it. Mobile version should be simple and fast. Constantly check your pageviews/visit, bounce, time. And if everything is ok then your linking fits visitors needs and same google needs.
Our implementation will be to serve different mobile content under the same URL. We're trying to keep the content on the page as close as possible to the desktop site but remove weight from the page to make it much faster.
One of the most expensive elements of the page in terms of page load is our current internal linking navigation, which for the mobile version we're planning to drop and move onto it's own page effectively. This will have a great page load speed impact, but I'm concerned that Googlebot-Mobile not having access to our existing internal links might cause some sort of problem.
We're going to try it out on the basis that our desktop site will still be the primary source of ranking information, and the mobile versions of the pages will be indexed as alternative versions of that site rather than as a site on their own with their own internal linking structure. That seems like a reasonable interpretation of all the documentation I've read so far from Google etc.
Any counter opinions?
Could you detail a little more how you would reduce the amount of internal nav on a mobile site without affecting how the site works. I'm have a hard time getting my head around that.
What about images? On an upcoming site, we have desktop images that are large. These would definitely need to be made smaller for mobile devices. I'm thinking these could have greater effect on load speed than nav would, albeit might not affect ranking nearly so much as navigation.
Thanks philipboyle, looks like we are in the exact same situation, and what you say is what I was hoping to hear. Still, Would be nice to have some hard evidence.
Robert Charlton: The basic navigation will be kept and adapted for mobile. The question is about the extra navigation we offer our desktop users, cross-linking, related links, etc.
Is there good way to serve two different types of images for desktop and mobile users?
@Robert Charlton: We have two main styles of pages on our site, list pages and product pages. Our internal links on the desktop version are shortcuts to other categories mainly. We're going to move those links onto a separate page on our mobile site, so you click the search icon in the top right and go to a dedicated navigation page with those links and a search box. It seems common enough functionally speaking on other mobile sites I've seen. We'll test it out and see how we get on!