There's only one version of Cameron's movie avalible at the present time, although there are plans to make a special edition dvd with a few extra scenes.

As for other movies on Titanic, you've got:

Saved from the Titanic - 1912 (starring Dorothy Gibson, who was a survivor)

Titanic - 1915 I believe this is an Italian version actually..
Titanic - 1943
Titanic - 1953
A Night To Remember - 1958
S.O.S. Titanic - 1979
Raise the Titanic - 1980
Titanic - 1984
Titanic - 1993
Titanic - 1996 (Catherine Zeta Jones version... I personally do not like this one)
James Cameron's Titanic - 1997
Femme de chambre du Titanic, La - 1997
("The Chambermaid on the Titanic)
Titanic Town 1998