Website Translated in Many Languages?

Do you know,can wp plugin for translation to other languages improve PR?

To my mind a translation plugin itself has nothing to do with PR straight. And remember that PR is counted not for a site, but for a single page.

you can rank to different language serps, but i don't think it will affect the PR...

I won't say that improves your PR but it very may well improve your Google's UX (user experience) score, which is starting to play an important role in the ranking algorithm.

Depends on what plug in you are planning on using. I doubt it would affect page rank any way but two things you should consider before you do it. If you add in a translator for say 5 different languages you will get 5 times the content indexed but will run into duplicate titles. Google say they dont penalise this too much but you can never be sure.

If you ever do a site redesign and decide to get rid of the translator then you are going to have a lot of 401 dead pages to re direct.
I would only add a translator for user experience. If you get hits from Italy and Spain then add the translator dont just add it for potential seo purposes.