Originally I recommended some time ago in the post https://premium.wpmudev.org/forums/topic/please-improve-the-preview-in-the-page-editor that a character counter be implemented into the tool, so that you could easily see how many characters your title included, and to make sure that it didnt go over 70 characters. This was actioned and it has been really useful.
Following some research by the team at SEOMoz, i'd like to suggest that the tool is modified so that rather than limit me to only 70 characters, it simply provides a warning that my title is over the 70 character recommendation. Maybe by changing the colour of the box or something similar?
For reference, the video presentation that explains why this is important is available to view at http://www.seomoz.org/blog/title-tags-is-70-characters-the-best-practice-whiteboard-friday
Thanks guys, and keep up the excellent work!