Has anyone come across any information about client side use of XSLT for XML transformations, and how that is going to impact on google rankings?

I know that google et al put a fair amount of emphasis on things like <h1> tags etc.

Basically am I comiting search engine suicide by going for the semantic web/web 3.0/whatever style approach?

As far as I know, XML is very basic and has no built-in semantics such as h1, h2, title, etc. While you can have those in your XML file, it won't mean the same if you use the proper xml content headers.

Why don't you do the XSLT transformation on the serverside so search engines get everything in HTML form?

Well XML is semantically vastly more powerful than HTML ever has been or will be!

There is no real reason for the XML delivery really - was just based on a discussion i was having with someone, i.e. all blogs are a page with a RSS feed, why not have a blog as a RSS feed with a page?