You can do it with the user agent in javascript or by detecting screen size There are plenty of examples out there. Google put out a blog post on this not long ago said redirect was fine, but should move towards responsive design.

I'm just getting into developing for mobile, so I sympathize. It's very difficult to find up-to-date information on this topic and several other related issues.

So far, I've learned just enough to make websites function reasonably well on smart phones, in the spirit of "responsive design" that phpguy mentions. Now I need to learn about the less intelligent phones, and I don't really know where to start. With regard to the issue of redirecting, it seems to me that in my current situation, I'm best off only redirecting those less intelligent phones. In checking my server logs, it looks pretty easy to pick off the iPhones and mobile versions of Andriod from the User Agent string, but I don't know which other phones are smart enough to deal with the "responsive" version and which are not. If there's a term of art that distinguishes these phones that I could search for, I haven't found it. Worst of all is the nagging feeling I have that, given the current half-life of cell phone ownership, their market share is likely to fall so fast that by the time I actually know what I'm doing there won't be enough of these phones left in use to matter.

Thanks for the comments. As for the redirect problem, it's not as simple as it looks initially. One apparently simple problem that many javascript solutions ignore is how to allow viewers to go back to the main site without then automatically getting redirected back to the mobile site. However, after two potential outsource options have backed off because of the complexity and my limited budget, I have designed a solution myself and it seems to work a treat. It works for html pages and javascript, if you want specific details of my solution then sticky me, any comments back would be appreciated.

I have however tackled the problem via a G approved, but not the number one recommended G solution. G are pushing the responsive design solution, I couldn't realistically make that work. So I have a .mobi version of the site. In my view, aside from the problems that responsive design imposes on a site, a separate site (or a subdomain) has one huge advantage, it keeps all the problems of evolving mobile devices well away from the main site. I don't have the money to invest in one ultra complicated site that caters for every different screen size so I am keping my main PC / laptop site
well insulated from the other tablet / smatphone / mobile site.

Will I get penalised for this approach? I am betting no. The main reason is that some very large UK sites have gone down the route of of a separate mobile / subdomain site for mobiles. One of the first I noticed many months ago, and well ahead of the competition, was the Jamie Oliver site (and no, I am most definitely not Jamie Oliver!). They have a separate sub domain for their mobile site and searching on Google with a mobile shows that the mobile site (not the main site) is the one returnd in the mobile SERPS.

And yes, rainborick, I agree, designing a version of a website for pre-historic mobiles is a waste of time. The only people using them are exactly the people who will never buy anything online or click on an ad. In fact the current course of developement looks suspiciously like the younger generation owning two devices - a mobile for making phone calls / looking up sports results and a tablet for browsing the intenet and playing games. It's the tablets which seem to be the market to aim for alongside laptops and PCs.

We're not very far apart. It's often impractical to try to translate an existing site into a responsive design version, and you can easily make the site pretty ugly when you do. I'm still trying to wrap my head around designing for screens that could be as small as 320x280, and wondering if those phones are as doomed as well.

I'm much less concerned about tablets, though. It seems to me that those screens are large enough to deal with a conventional desktop/laptop site, even if it means the user will be scaling in and out. And since those users won't often be standing or otherwise "on the go" like a cell phone user might well be, it's not nearly as much of an inconvenience for them. So lumping them in with mobiles just doesn't feel right.

I'm now at the same crossroads that nomis5 faced. I just deployed a mini-site after redesigning the client's primary site for responsive design. I set the mini-site at a fixed width for now. The primary site functions well on smartphones (iPhone and Androids), but it just wouldn't squish down to 320px - which leads to a couple of questions.

1) How do I best redirect just the feature phones to the mini-site or all mobiles?
2) Should I redirect non-mobiles back to the primary site or is the <link rel="alternate"> sufficient?

The client is a service business which makes mobile users an important target market, so I want to be as smart as I can here. I can live with sending smartphones to the mini-site, despite its limited visual appeal, in order to maximize the effectiveness. And should the day come when feature phones are no longer significant, I can always shut down the mini-site and take advantage of my work on the responsive aspects. But I've gone over Google's advice several times and it hasn't answered these questions for me.