For my write-up today on volume 3 of John Meier's A Marginal Jew, Rethinking the Historical Jesus, I'll use as my launch-pad some of what Meier says on page 567, where Meier summarizes what he considers to be Jesus' interaction (or lack thereof) with certain Jewish movements.
Regarding the Essenes, Meier sees no evidence that Jesus interacted with them, though he is open to the possibility that Jesus distinguished his own teachings on the law from theirs. Meier's discussion of the Essenes had interesting material. One point Meier made was that the Qumran Essenes waited for an eschatological Temple to supplant the current Jerusalem Temple, which they deemed to be corrupt, on account of its different calendar. In the meantime, they treated the Qumran community as a sort of Temple in itself, in which members worshiped with angels; consequently, some of them were celibate (since the Torah sought to separate sexuality from the sanctuary), and they had strict rules on (say) not defecating on the Sabbath. Another motivation for such rules, according to Meier, was probably that the Qumranites regarded themselves as part of a holy army, and avoiding sex was part of being a soldier of God. Meier also demonstrates that some Essenes were not celibate, and that some were more integrated into mainstream society than other Essenes. And Meier refers to the economic egalitarianism within Essene communities, as they attempted to avoid the concentration of wealth and power that was a bane to all sorts of societies, including the Judean one.
On the Samaritans, Meier states that it's multiply attested that Jesus had a benign stance towards this maligned group. I did not get whom exactly Meier believes that the Samaritans were, but he does appear to dismiss what he considers to be myths concerning them. First of all, Meier has issues with II Kings 17's claim that the Samaritans were half-Israelites who resulted from the foreigners whom the Assyrians imported into Northern Israel mating with the remaining Israelites. Meier contends that most Northern Israelites remained in Northern Israel rather than being exiled, and he states that it was primarily the small elite that had the foreigners. Second, Meier does not think that Samaritans were the ones who challenged Ezra and Nehemiah. These enemies' headquarters had no association with Gerizim, the mountain that the Samaritans revered. Third, Meier appears to be skeptical that there was a rift between the Samaritans and the Judeans, for that implies that the two were united at one point. For Meier, the Samaritans and the Judeans drew from a common ancient Israelite religion, but he must think that their situations led them onto separate paths, not that there was a dramatic rift.
On the scribes, Meier says that the Pharisees and the priests had them. (On pages 550-551, Meier briefly yet aptly discusses the development of scribalism: that scribalism developed with urbanization, tax-collection, and militarization, as scribes were needed to record information.) But Meier believed that the portrayal in the Gospels of the scribes as Jesus' opponents reflects "later theological debates, not the historical record" (page 567).
Regarding the Herodians, Meier defines them as members of Herod's court and as supporters of Herod. He speculates that their problem with Jesus was the fear that he could become a king or a Messianic pretender, for they hoped for Herod to be king.