The Volcanism Blog has also been covering this developing story. Today he has posted a summary of available information, along with an extensive set of links to news reports and other sources of information. Yesterday, he posted an extraordinary sequence of still photos, and later linked to the BBC video from which they were taken. Those two posts and two other earlier posts can be seen under the Tonga tag.
This seems to me to have the makings of a fascinating eruption, from which the volcanology community will learn a lot, or a horrifying disaster. Or, I hate to say, both.
Followup (6:40 PM) Hadn't got to this piece yet... The Big Picture has a very nice photo set of this eruption.