Good PR, you know. (A factoid I learned from FreeRepublic, by the way.)
History of Greenland (Wikipedia)
"There are two written sources on the origin of the name, in the The Book of Icelanders (Íslendingabók), an historical work dealing with early Icelandic history from the 12th century, and in the medieval Icelandic saga, The Saga of Eric the Red (Eiriks saga rauða), which is about the Norse settlement in Greenland and the story of Eric the Red in particular. Both sources write: "He named the land Greenland, saying that people would be eager to go there if it had a good name."
So it probably wasn't really very green, but Erik the Red wanted people to think it was. Settlements did hang on for awhile there -- the article has a good summary.
I found this source to be more well-researched and accurate than Wikipedia about the lifestyle of the Vikings there:
http://www.archaeology.org/online/features/greenland/
In short, they could not have developed such a social structure without the benefit of better environmental conditions than exist today.
To prove that it wasn’t all in a name: wasn’t it Iceland where they used to grow grapes?