Is it permissible to move large, heavy furniture on Shabbat, such as large tables, couches and beds, or does large furniture have the status of "Muktzeh" such that it may not be moved on Shabbat?
The Gemara in Masechet Shabbat (35a) cites a debate between Rabba and Rav Yosef as to whether one may move a large utensil that can contain a volume of three "Kor" (a Talmudic unit of volume). One view maintains that a utensil containing three "Kor" or more is deemed Muktzeh, while the other contends that this status applies only to utensils that contain at least four "Kor." Both Rabbis agree that utensils capable of containing four or more "Kor" are indeed considered Muktzeh and may not be moved on Shabbat.
Tosefot (compilation of Talmudic commentaries by Medieval French and German scholars), however, claim that Halacha does not follow either view. They cite a passage in Masechet Eruvin (102a) which tells of a heavy beam that could be moved only with the combined effort of ten men, and yet was not considered Muktzeh on Shabbat. Likewise, the Gemara later in Masechet Shabbat (45b) allows moving a large canopy bed on Shabbat. Based on these Talmudic passages, Tosefot assert that according to the accepted Halacha, neither size nor weight affects a utensil's status with respect to the laws of Muktzeh. The Shulhan Aruch (308:2; listen to audio for precise citation) codifies this ruling of Tosefot and rules that weight and size cannot render an item Muktzeh; this is indeed the accepted Halacha.
Summary: It is permissible to move large, heavy furniture on Shabbat, even if they require many people to be moved.