A WebmasterWorld thread says that Google has increased the title tag limit from 66 characters to 70 characters. By that I mean, some are reporting Google is showing the blue clickable link with a maximum character limit of up to 70 characters, which is up from 66.
Some are even saying that the title tag is wrapping to the second line. Personally, I do not see that but I am seeing some titles that are up to 69 characters and I am sure if I dig around enough I can find some that are 70 characters long.
Tedster, the WebmasterWorld administrator, validated this observation by saying:
I think you're right - I am seeing 70 characters on some titles, although in my browser, it's still just one line. Can't say for sure when that change happened, though.
Some are saying this dates back to March but I am not sure if anyone noticed back then.
Forum discussion at WebmasterWorld.