JR Sendai has published a list of the train lines that are expected to be back in operation by the first week of April or so -- they're making rapid progress and some lines around Sendai will start operating shortly, but Sendai will still remain cut off from the bulk of the network. Also, while the Yamagata Shinkansen will start operating between Yamagata and Fukushima soon, there's still not even an estimated date for resumption of the Tohoku Shinkansen.

http://www.jr-tabi.com/eq.html

More positively, and in fact rather incredibly, all major roads in the Tohoku region, including the worst-hit Sanriku coast are, are now usable and open to the public again (excluding the nuclear plant exclusion zone, that is). Only some expressway sections around Sendai remain reserved for emergency vehicles.

http://www.mlit.go.jp/common/000138153.pdf