Tips for hiking safely in Tahoe in the wintertime:
1: Carry a protein bar and thermos with hot liquid like green tea
2: Wear lots of layers: Snowsuit, thermals, T-shirt, down jacket, etc.
3: Know your trails and be aware that the snow may be deeper than you think
4: Have a cell phone with you and charged in case you get in trouble.
If you have an Android phone you may find these apps from Android Market helpful:
Tahoe Daily Tribune
(See: http://www.youtube.com/watch?v=NZbrmSDiKHE for more info)
American Red Cross