The post indicates a growing problem with cheaters, though the catalyst behind the announcement remains unclear. What is clear is that Blizzard takes cheating very seriously, and those caught out can expect a severe reprimand.
The post on Battle.net reads: "If a Diablo III player is found to be cheating or using hacks, bots, or modifications in any form, then as outlined in the Diablo III end user license agreement, that player can be permanently banned from the game. This means that the player will be permanently unable to log in to Battle.net to play Diablo III with his or her account."
They then sum up with: "We strongly recommend that you avoid using any hacks, cheats, bots, or exploits. Suspensions and bans of players that have used or start using cheats and hacks will begin in the near future."
You have been warned.