Actually, there are two forms of the elipsis: three dots ( . . . ), indicating that something has been omitted within a sentence, or sometimes tying two sentences together; and four dots, indicating that the omission comes at the end of a sentence or paragraph, thus. . . .   The latter case is often used informally as a means if indicating an incomplete thought, presuming that the reader can fill in the rest.

Spacing is also regarded as important when typing a manuscript. In the three-dot ellipsis, there should be a space following the last letter of the preceding word, a space between each dot, and a space preceding the first letter of the following word. In the four-dot ellipsis, there should be no space between the last letter of the preceding word and the first dot, but a space between each dot. There should be two spaces following the fourth dot.

Or so says my style manual, which has a good section on preparing manuscripts for publication.

Don Firth