One of the neater things about Mowser is that the content adaption process leaves all Class and ID names intact, and passes through any handheld stylesheets that may be on a publisher's server. This allows publishers a level of control over the look and feel of their adapted pages since they can still modify the style of those Classes/IDs. The problem, of course, is that not many sites bother with handheld stylesheets, so this is only a benefit in a sort of academic way.
I was just looking to add in a handheld stylesheet and header into the Mowser WordPress plugin I just posted about, and happened to run across a post about Opera Mini 4 published over at Unintentionally Blank about this very topic, published *just today*. Wow... In the post, Phil points out that Opera Mini 4 has gotten rid of defaulting to the handheld stylesheet, unless you've explicitly chosen to turn on Small Screen Rendering ("Mobile view") in the settings. Interesting! Opera has been one of the leading promoters of Handheld styleseheets, and their Opera Community site is still the best example of how to use it on the web today.
By choosing to default to non-handheld views, I have to agree with Phil that Opera seems to have given up the fight on this particular battle, and is instead banking on more sites using CSS3 instead. Like the iPhone's mobile Safari browser, Opera Mini supports CSS3 media queries which lets you modify the style based on "media features", which include among other attributes, height, width and color. In other words, instead of requiring that the device know that it's a handheld (or in Internet Explorer's case, that it's *not* a handheld) in a boolean yes/no manner, CSS3 allows the publishers to design based on a device's specific capabilities.
I have to say, this is a much better way to specify formatting - I'm just amazed at how quickly it's being adopted (though there are others who called it back in July)... Opera Mini is the most popular mobile application on the planet, so it's non trivial that it's going to be ignoring handheld stylesheets by default. And since handheld stylesheet support is sketchy at best in phones already, I have to think this is the end of the line.
Soo! It looks like I have some work ahead of me. I've been meaning to add in specific CSS processing to Mowser - for example, cutting out anything marked display:none at the server, cutting down on transfer time to the handsets - but this gives me even more reason to. Mowser is essentially a standard browser on the server, which lets publishers know their content is being seen by any handset with the same sort of quality as someone with an iPhone or using Opera Mini, so if these guys are supporting these things, I better get to it myself!