Here are some usefull resources on how to change the way your field is rendered in SharePoint 2010 Lists
1. SharePoint uses XSLT to render the views in SPS 2010. Here is a sample on how to customize the rendering of a field
http://msdn.microsoft.com/en-us/library/ff606773.aspx
2. The <xsl:template … element requires a mode attribute. Here is how to find the mode attribute for your field type
http://www.silver-it.com/node/66