in 2005, the ability the reply using an account was the norm, where replies could be rated 1-5 (slashdot and the rest).
In 2010, upvoting messages by giving them points was the norm, which Digg started and Reddit perfected.
In 2015, labelling posts I think will be the norm. Users will get the ability to associate posts with labels, such as insightfull, funny, interesting, firstpost, nonsense, et cetera. Every post will get it's own tagcloud, the labels being associated a lot being bigger.
The problem with upovoting is that you only classify posts using a numeric value. A numeric value can only express a limited classification. It does not say anything more specific then "bad rated" (<1), "not rated" (1), "somewhat rated" (>1 <6), "good rated" (>5 <20), and "awesome" (>20). Other then that, it does not say anything useful.