i have a site who have a 50 penalty he go from page rank 2 to 3 today maybe the penalty have be left? and i need i wait google refresh my homepage for see change in serp for moment i have always a 50 penalty its possible a site who have a penalty go from 2 to 3 in pr update?
yes, its possible. PR is PR, SERP is SERP. sometime you can even see a page got penalty on some keywords but not others
PR doesn't have anything to do with penalties really. Anyway, your PR didn't change, your visible PR changed. The actual PR that counts in the algorithm updates constantly just like every other factor.
One of my site got -30 penalty and lost PR, but one got penalty and got PR1, may after some days or in next days, it come back.