What's better than mirror lock? Electronic shutter curtain.

I found this on Michael Covington's site:

"One of the least-known features of the Canon EOS 40D and many of its relatives (including, as I understand it, the XSi) is the electronic first shutter curtain."

"Canon DSLRs have the ability to begin the exposure electronically with zero vibration."

More here:

http://www.covingtoninnovations.com/michael/blog/0910/index.html