First posted 28 May 2008; update below
Lusi is that big mud volcano that started erupting two years ago  on Java. Unlike most mud volcanoes, Lusi was triggered by a drilling mishap and has buried several hectares of the town of Sidoarjo. An upcoming paper in Environmental Geology (see the press release) documents the beginning of Lusi's collapse. Eventually its central area will subside some 140 meters into the ground, creating a caldera. I've bookmarked Lusi in Google Maps for you as new photos supersede old ones, we should be able to watch the process happen. In today's image, the collapse is not obvious. Chris Rowan at the Highly Allochthonous blog has some well-dated images, and it looks like Google Maps is more than a year old. He also has a fresh update discussing this same paper.
UPDATE: I've brought the links up to date but left the text of this post alone. Almost five years later, Lusi is not showing any obvious caldera. Knowledgeable people are invited to review and continue the comments, which have been most interesting. Also, for your reference, here are all of Chris Rowan's Lusi posts.
Mud volcano, Salton Sea Geology Guide photo