Shrine

Shrines are not yet confirmed in Diablo III. The D3 Team has mentioned them[1], and said they're tossing around ideas about how to implement them, but nothing is set yet. They want shrines to return in Diablo III, but they want to improve them, and make them more useful and important.

Jay Wilson has pointed out that the Shrines in Diablo II were not very well implemented, since their bonuses were not relevant to the levels they were found on (lightning resistance shrines on levels without any monsters that used lightning attacks, for instance), and most of the bonuses weren't very useful or fun. Everyone loved Experience shrines, and Monster shrines were fun, but the rest were pretty much ignored, or of not special importance.

Shrines in D1 and D2

Read about how shrines were implemented in Diablo 1 and Diablo 2.