In my Gmail inbox, when there is a mail sent by somebody I have in contacts, I don't see the sender's real name. For example I have Jan Novak in contacts, his email is jannovak.cz. When he sends me a mail I see "jan" and not "Jan Novak" in my inbox. Is there a way to change this?

I am quite sure Gmail simply emits what the sender supplied in the headers, no local embellishment from the Contacts is done. Check the "Show Original" option on that Czech ;-)) you'll find that his "From:"-line lists just jannovak.cz.

Thanks... I think that there should be a labs feature that will show the name from contacts.