WBUR has special coverage that is pretty informative (as much as it can be at the moment). Robin Young is on right now, she met the younger brother at a prom party she threw for her nephew (who was friends with him). http://www.wbur.org/listen/live
Press briefing in Watertown soon.
ETA (because I have not seen it on Jez, but it's on Gawker): MIT officer who died is 26-year-old Sean Collier, formerly worked with Somerville PD. Very sad.