Multiple themes in dynamic blogs?

So, I’m working on a redesign for this blog, but I don’t want to put it up until I can find a way to keep the old posts on the current theme.

I can’t seem to find a way to do this with WordPress, or any other blogging tool. MoveableType may be able to do it, but I’d prefer to stay with open source.

Any ideas?

2 Responses to “Multiple themes in dynamic blogs?”

  1. Peter J. Says:

    If you’re going to stay with similar HTML and just change the CSS, perhaps something like the FOAF Header would work? The idea is essentially to define a custom field that can then be used where you link to the stylesheet in your header.php.

  2. ryan Says:

    I actually want to be able to change the HTML.

    Essentially what I want is a static site + comments. Maybe I’ll have to build my own.