What is the significance of the phrase "Baruch HaSh-m E-lokei Shem," and what is the connection to the second half of the Pasuk, "And Kena'an shall be a slave to them"?
Ramban: "Baruch HaSh-m E-lokei Shem" signifies that Shem is a servant of HaSh-m, and the Pasuk adds that Kena'an is an Eved to him and his children (or to Shem and Yefes).
What is the connection between the Berachah that Noach gave Shem, and the curse he gave Cham?
Rashi: Noach blessed Shem inasmuch as HaSh-m would fulfill the promise He would make to his children (Avraham, Yitzchak and Yaakov) to give them Eretz Kena'an (Kena'an's land), and cursed Kena'an, in that they would become their slaves.
What did Noach mean when he said that Kena'an would be an Eved "to them"?
Ramban #1 (citing the Ibn Ezra): He cursed Cham that he would be a slave to Shem and to HaSh-m, in that the former will force him to serve the latter.
Ramban #3: He will be a slave to his brothers, i.e. everyone.
Seforno: He cursed him that he would become a slave to the G-d of Shem, and to Shem's children, as "wood-choppers and water-drawers for the Mizbe'ach and for the community." 3
Targum Yonasan: Even though it is written in the plural, it is referring exclusively to Shem the Tzadik.
Rashi writes: "Blessed is HaSh-m - Who will in the future fulfill His promise to Shem's descendants...." How is this derived from the verse?
Gur Aryeh: Otherwise, why does Noach express his blessing [towards HaSh-m] at this point? Noach foresaw that HaSh-m would fulfill His promise to Shem and give him Kena'an's land.
רש"י: שעתיד לשמור הבטחתו לזרעו: מנין שזו הכוונה?
גור אריה: אין שייכות ל"ברוך" כאן אלמלא שראה שה' יקיים הבטחתו לבניו.