Yes, People do write handwritten thank you notes because, No, the age-old statement of gratitude is not dead. Yet. But Kennedy is right; things have changed since the days of the ten cent stamp. Here's how it's done well these days:
First, make sure you pick up a business card or accurate contact information at the interview. This is critical, because it can be hard to go back and find an email address when you need one. If you're the plan ahead type, you can gather this important information when confirming the interview. It is entirely appropriate, when scheduling any meeting, to ask for contact information. Then file it away until you need it.
Next, the minute you leave the interview, compose a rock star thank you email, and send it.
For bonus points, you might want to tweet something positive at the company. "Just left @abccompany Incredible warehouse" or something like that. Realize, the person who interviewed you might never see that, but others might, so be smart there.
Finally, grab that simple note paper and envelope and write a real, ink to paper thank you to each person who interviewed with you. Stamp and mail those on the day of the interview. Things move fast, and you don't want to have to rewrite it if something changes overnight.
Things do not always move fast, however, and this is why the written thank you note has always been a good idea, and will continue to be. When your letter lands on someone's desk, if he or she has not followed up with you, this will prompt them to do so. And if you've already had a second and third interview by the time the snail mail arrives, it can seal the deal on your behalf because there are many, many people competing for work out there, and most of them won't bother with this extra step.
In summary: send the email thank you because you are current and on pace with the rest of the world; then follow up the old fashioned way. Even though people don't always bother to mail a thank you, people always appreciate receiving one.
Julie Desmond is IT and Software Recruiting Manager with George Konik Associates, Inc. www.Georgekonik.com and on twitter @MNCareerPlanner