Short answer, yes, e-mail is acceptable. You bring up the main reason in your post: "snail mail" may not reach your recipients until too late.

However, there is an exception: if you were asked to mail in your resume, as opposed to e-mailing it or filling out an online form, then I would send thank yous through the postal service. A trick to getting those letters out sooner, if you know for certain who will be speaking with you: write out your thank-yous ahead of time, and preaddress them. Once the interview is done, you can slip them in the nearest mailbox.

If you had the option of e-mailing your resume, or if they insisted on it, than I would use e-mail for your follow-up.

Best of luck!

My standard approach for academic library interviews in the US was to email thank yous after a phone interview and hand write thank yous after an in-person interview. This changed when I applied for my current position overseas--snail mail just wasn't practical.

Either way, a thank you note will distinguish you from the pack. I'm amazed at how many people don't perform this simple courtesy.