Yes they can be graded but not under sealed games grading, under Qualified Grading Scale only.
This is when an item never came sealed and as such the box and content are inspected and given a grade based on their condition, instead of a seal.
See hear:
http://www.vggrader.com/faq.aspx#loose
Edit: yes Uncharted 2 Fortune hunter edition can be graded under QGS