Having worked in Kindergarten for 3 years specifically and then several grades this year, I think a realistic standard is:
know letters (or at least a decent percentage of them, or knowledge of alphabet)
counting to 20(difference between numbers and letters)
basic shapes (circle, triangle, square, rhombus, oval, rectangle)
basic colors
write first name
knowledge of books (know that you read left to right, how to hold a book, etc.)
You'd be surprised how little some kids know and how much others do. They have to be taught things in kinder, however, a basic knowledge will allow them to succeed and be strong students.