Among the changes coming to Diablo III are completely revamped legendary items. Senior designer Andrew Chambers notes:
In many ways the Legendary items that we released with the game were just Rares with flavor text. You called us on it, and we’ve listened.
The updated legendary items will have new visuals and — more importantly — new custom effects. This will be part of the 1.0.4 update due by the end of August.
In case you’re considering going to hunt down a few legendaries now (i.e. scour the auction house for a good deal before these items get better), hold on a sec.
…these changes will only affect Legendary items that drop after the release of patch 1.0.4. This includes items that haven’t been identified yet (as items are rolled when they drop).