I bet this was suggested before.. x-x;
I think this would be a great option. I say option because some people wouldn't want the last time they've login to be so public (such as sneaking on occasionally).
It would also be great for those impatient people waiting for other people, so they won't rage as much. They can only stalk. xD
I know some people will most likely rage if that person was on the day before, but they'll quiet down if they actually knew the person wasn't on for a few days.
Given the current circumstances, some people will rage regardless because they don't know when the person was even last online.
It could either portray a date so vague (like September 30th, 2011) or something really specific (September 30th, 2011 01:45:24 PM).