http://www.reddit.com/r/Guildwars2/comments/z3qqm/guild_wars_2_status_thursday_august_30/
Well worth a read.
A lengthy article (https://www.guildwars2.com/en-gb/news/mike-obrien-on-account-security/) from Arenanet.
It would be wise to heed the advice, forced password changes should be on the way.