The Gemara in Masechet Berachot (41) discusses the status of fruits which are eaten as dessert, and are not an essential component of the meal. Such fruit, the Gemara establishes, is not considered part of the meal, and it is therefore not covered by the Beracha of "Ha知osi" recited over the bread at the beginning of the meal. Hence, one is required to recite a Beracha over fruit eaten as dessert after a meal, even if it is eaten before Birkat Ha知azon.
Tosafot, commenting on the Gemara, add that in principle, one would also be required to recite a Beracha Aharona over this fruit, as well. Just as the fruit is not covered by the Beracha recited over the bread at the beginning of the meal, it is likewise not covered by Birkat Ha知azon recited after the meal, and so one would be required to recite a Beracha Aharona after eating the fruit. However, Tosafot then clarify that this Halacha does not apply as a practical matter nowadays. Tosafot explain that this rule was relevant in Talmudic times, when it was customary to remove the table before dessert, such that the dessert was clearly not part of the meal. Nowadays, however, when dessert is eaten on the same table as the meal, the dessert is included in Birkat Ha知azon. Therefore, although one recites a separate Beracha before eating the fruit, he does not recite a separate Beracha Aharona after eating the fruit. The Shulhan Aruch (Orah Haim 177) rules accordingly, that if the original table remains in place for dessert, as is customary, then although one must recite a Beracha before eating the fruit, he does not recite a Beracha Aharona on the fruit, as it is included in Birkat Ha知azon.
Nevertheless, there is a practical application of Tosafot痴 ruling, even nowadays. Hacham Bension Abba Shaul (Israel,1924-1998) notes that at some weddings, the tables are removed after the meal and the dancing is held in that room, while dessert is served elsewhere. If the tables are removed before Birkat Ha知azon, Hacham Bension writes, then one who eats fruit for dessert would be required to recite both a Beracha before eating the fruit and a Beracha Aharona after eating the fruit, before Birkat Ha知azon. Since the tables are, in fact, removed before dessert, Tosafot痴 ruling is applicable, and a separate Beracha Aharona is required.
A more common application of Tosafot痴 ruling is noted by Hacham Ovadia Yosef, who maintained that removing the tablecloth is akin to removing the table as far as this Halacha is concerned. People often clear the table and set a new tablecloth for dessert, and Hacham Ovadia rules that in such a case, if one eats fruit for dessert on the new tablecloth, then he must recite a Beracha before eating the fruit, and also a Beracha Aharona after eating the fruit, before reciting Birkat Ha知azon.
Summary: If one eats fruit for dessert at the end of a meal, he recites a separate Beracha before eating the fruit, but does not recite a Beracha Aharona after eating the fruit, as the fruit is covered by Birkat Ha知azon. However, if the table or tablecloth was removed before the dessert was served, then one must also recite a Beracha Aharona after eating the fruit, before reciting Birkat Ha知azon.