During the Prop 8 trial, the best source of info I found was the liveblogging at Firedoglake. (I keep meaning to send them a donation in appreciation.)
They'll be liveblogging the closing arguments as well, starting about nine hours from now (that is, around 10 a.m. California time on Wednesday the 16th). They've posted a tentative schedule. For links to their liveblogs, keep an eye on their Prop 8 trial hub page, or visit the two blogs (The Seminal and Emptywheel) directly.
I imagine various other bloggers and organizations will be tweeting and liveblogging during the day as well, but I'll mostly be watching FDL.