I\'m trying to save date (using C# official driver):
val = DateTime.Parse(value).Date; //Here date is {11/11/2011 12:00:00 AM}
var update = Update.Set(\"Date
You're running into a timezone issue. Your date object is probably in a timezone other than UTC (2 hours ahead by the looks of it) or your default timezone is set to something other than UTC. The driver will convert the date to the appropriate timezone before storing it in the database.
Normally you wouldn't notice this since the reverse (retrieving the UTC date from the database) should convert it back to the original timezone. There might be an issue with the driver you're using or C# might require a bit more code to get it right.
Storing dates as strings is usually not a good idea since it disables range queries on dates.