Times have certainly changed with respect to communications. The PMBOK Guide and other PM resources tell us the difference between formal (letters, written reports, major presentations) and informal (emails, phone calls) communications. Unfortunately in our instant communication age, emails and IMs often replace what should be more formal communications.
Emails may be fine for some companies and some project teams, however before making the assumption that emails will suffice for all, I would make a formal list of all the stakeholders, the communications they need to receive, and by what means they should receive them. Remember that often you are not just updating stakeholders on project progress -- you are often "selling" them that your project is going to provide useful results for them.