With electricity supplies stabilizing, and demand low thanks to warm 
weather, trains in the Tokyo area are running on a stable basis.

On most non-JR lines, trains are running full force during the morning 
rush and on a reduced basis during off-peak hours.

JR East commuter-train operations are mostly normal in the Tokyo area. 
There are no reductions during off-peak hours.

Seibu will reduce weekday off-peak runs from April 25.

Tokyo Metro will change its weekday services somewhat from April 25. 
Through trains between Subway Hibiya Line and Tokyu Toyoko Line will run 
during peak hours (but not during daytime.)

Tohoku Shinkansen will resume services to Sendai on April 25.

Details here:

Trains in the Tokyo area:
http://www46.atwiki.jp/earthquakeinfo_en/pages/40.html

Transportation in the Tohoku area:
http://www46.atwiki.jp/earthquakeinfo_en/pages/15.html