Check out the Windows Internet Explorer weblog to see what you need to check in your code to make it compatible:
http://blogs.msdn.com/ie/archive/2009/03/12/site-compatibility-and-ie8.aspx [6]
Nice to see more support for standards!
Links:
[1] http://pulse.veltsos.com/category/it/browser
[2] http://pulse.veltsos.com/category/it/software/software/os/microsoft
[3] http://pulse.veltsos.com/category/it/software
[4] http://pulse.veltsos.com/category/it/web
[5] http://linux.philosweb.com/drupal5/files/IE8_logo_2.jpg
[6] http://blogs.msdn.com/ie/archive/2009/03/12/site-compatibility-and-ie8.aspx