I would like to apply layout templates to my posts, just like I can do with pages. For example, I have a template-wide.php that does not include sidebars and adds a special “wide” class to the content div.
At present, I can only use this template for pages. Is it possible to make it available to posts as well?
Use the Custom Post Template Plugin.
WordPress 3.1 includes a new feature called Post Formats. It’s a little like how Tumblr lets you have different formats for different kinds of content, and I think it could be adapted to what you are trying to do. I haven’t actually used it yet, but here’s an introduction I found that might be helpful.