Alongside the new story episode (opens in new tab) and sprawling Silverwastes jumping puzzle, last night's Guild Wars 2 update also brought an overhauled PvP mode.
"Player vs. Player infrastructure is seeing massive changes this month," explains the Guild Wars 2 release page. They've merged the Team and Solo arenas into a single "Ranked" mode—allowing parties of any size to participate in the most competitive mode. An "Unranked" arena has also been added.
In addition, matchmaking has been improved to search via a number of criteria, and leaderboards, map voting and disconnection penalties have all been changed. There's a full overview available on the release notes page (opens in new tab).
This, seemingly, marks a shift in strategy for ArenaNet's updates. Over the last year, feature tweaks have been held off for large "Feature Pack" releases, with the Living World updates focusing primarily on content and story. Here, they've again been merged—although there's no word on whether this is a one-off for this release.