I showed recently Google will use the next available Header, be it a H1, H2, H3, H4, H5 and H6 if your page title element is screwed.

The snippet below shows Google using a H6 header as the page title.

http://www.hobo-web.co.uk/seo.html

Yahoo will actually ignore the Header tags on the same page and elect to use the anchor text of incoming links

Yahoo

MSN / Live seems to just go for it, and index the title as much as possible (@ 75 characters?)

MSN

Did you know when you link to a Hobo SEO post we have search engine friendly links back to your site if approved? Our comments are also search engine friendly you know (once you've commented on a few posts)! Do you need any more encouragement to get involved in the conversation ;)