git status – list last modified date

Not directly but you can use a pipe:

Note: original answer updated based on comments

Linux:

git status -s | while read mode file; do echo $mode $file $(stat -c %y $file); done

Windows:

git status -s | while read mode file; do echo $mode $(date --reference=$file +"%Y-%m-%d %H:%M:%S") $file; done

OSX (source):

git status -s | while read mode file; do echo $mode $(stat -f "%Sm" $file) $file; done|sort