Mr Patterson, UCB, introduced Recovery Oriented Computing. In the article, Recovery-Oriented Computing (ROC): Motivation, Definition, Techniques, and Case Studies, an undoable email system was presented. This reminds me of Gmail which is the only one that I know, that provides a 'undo' function.
Recovery Oriented Computing is not a new idea. Things like checkpoints do just the same. Reliability or Dependability is quite important on High Performance Computers. However, it is equally hard to implement a fully reliable system that meets the performance requirements. Then checkpointing and rollback is an option. Recovery Oriented Computing showed why it is necessary and how to implement it.
On the other hand, Gmail is a new technology based product. Many big ideas like tagging, search not sort, dialog, combining with IM and AJAX were added to help improve performance, flexibility and change the way that emails were used. Compared to old plain text email system, which I believe was still used on many Unix systems, Gmail has countless advantages.
Either you do things ahead, or you do them faster. Theories are often ahead of times. They lead the technology. Theories, especially in engineering, require the support of experiments. Such experiments might be very difficult or costly. Thus supporting is somewhat important. Technology makes use of theory. The sooner you make use of advanced technology, the more you will benifit. Racers running faster reach the finishing line earlier than those slowers starting at the same line.