I know some about his expedition, such as the fact they were attacked by a (presumably Dorset) whaling party and driven off, after some sort of excitement about the bull they had with them. They were terribly afraid of the float-bladders attached to the whaling harpoons (at least, that's what they are interpreted as being, the Norse didn't seem to know what they were). Freydis does something startling to save the day ...
He's mentioned in Erik's Saga, there is a translation here:
http://www.sagadb.org/eiriks_saga_rauda.en
Go to Chapter 12 for an amusing bit from Karlsefni's expedition.
The expedition also seems to be recounted in the Greenland Saga, but the story is somewhat different. The incident with the ox is recounted, but the Norse send the Skraelings packing (rather than the other way around) and Freydis is a grasping schemer, who plots against Karlsefni's men on the expedition, falsely accuses them of molesting her, has her men capture them while they sleep, and then murders all of them with an axe.
Translation of that saga here:
http://www.northvegr.org/lore/flatey/001.php
There may have been two expeditions under Karlsefni, ie they wintered in Greenland and then returned in the spring.
Edited by edgewaters - 06-Mar-2009 at 03:17