Today is the 14th of Shebat 5770
Tomorrow, Shabbat, is the fifteenth day of the month of Shebat, the New Year - Rosh haShana- of the Trees. In our community this festival is mainly known as "Ilanot" (trees).
Tu Bishbat considered the Rosh haShana of the trees in the sense that the trees become one year older, not one year after they were planted, but on the 15th day of Shebat.
Most of the rain of the previous year, in the Land of Israel, have already fallen and a certain percentage of the fruit has reached the stage of "begun to ripen." This is defined as from the time of blossoming until the fruit has reached one third of its full growth. Fruit which have reached this stage, at Tu Bishbat are attributed to the previous year. Any new blossoming of fruit after this day is a result of the blessings of the new year.
Today, outside the realm of agriculture and tithes, the custom on Tu B'Shvat is to eat fruits from the seven species for which the Land of Israel is praised: "...a land of wheat and barley and grape and fig and pomegranate, a land of olives and honey (dates)" (Deut. 8:8). It is a special Zekhut to eat fruits which actually come from the Land of israel and say Berakha for them.
No special prayers are added to the regular prayer services but Tachanun (or Tsidkatekha) is not said.