Giacomo - 10:52 pm on Jun 1, 2010 (gmt 0)
As far as I now, this isn't new stuff at all: Google has been displaying 70-character long titles on SERPs for years now.
In my experience, Google will display at most 70 characters (whole title), or the first 66 characters plus an added trailing " ..." (truncated title).
The visualization algo seems to be something along the lines of: IF the title tag content is longer than 70 characters, THEN truncate it after the last word not exceeding 66 characters (overall length) and add a trailing " ...", ELSE display it as is. (Yes, it's that simple).