After the updates of 25 March, 2009, the appearance of equipped dragon platelegs slightly changed with the addition of spikes to the knees.
Upon getting Dragon platelegs, in the Adventurer's Log, it will say "After I killed a [Bronze/Iron/Steel dragon], it dropped dragon platelegs."
Dragon platelegs have experienced a dramatic drop in price from around 1,000,000 coins to under 160,000. This could be due to a number of reasons, such as rising supply, less demand, or more use of other popular types of leg armour such as Bandos tassets, Barrows, etc.
In My Arm's Big Adventure a captured Adventurer has his Dragon platelegs kicked across the Troll kitchen by the Troll Cook Burntmeat. Burntmeat discovers Goutweed inside the platelegs and interrogates the Adventurer about it before boiling him into a stew.