Just making a note of this for my future reference and for anyone else interested. This is based on Wordpress 2.8 but may possibly work with both older and newer versions.
To start with I wanted a way for an author to upload a profile photo directly to a Wordpress installation without having to sign up to a 3rd party site (Gravatar, etc.). I then wanted to display their picture on the author.php page. The fix for this was simple thanks to the 'Author Image' plugin (developer's site).
Next I wanted to put the author's description/biography on the page too. This is achieved by adding the following line in the appropriate place in the author.php file: (sorry it's an image as Blogger didn't like me trying to put it in to my posting :( )
I'm not sure who to credit for that as it's something I put in an older version of my modified templates, but thanks to whoever provided it originally and I hope this is useful for anyone.