I am Australian, and because of the song "Waltzing Matilda" which is basically our unofficial national anthem, the name is not widely used. However, there is now a character on the Australian tv show "Home and Away" named Matilda so my prediction is that it will get more popular in the next few years. In Australia, anyway.
This name was out of the top 1000 for decades until 2008-- I am sure Heath Ledger's death has influenced the increased popularity (it's his daughter's name).
This name is more popular in Australia than anywhere else in the world - it's a Top Twenty name.
Because "Waltzing Matilda" is our national song, Matilda the Boxing Kangaroo was our mascot for the 1982 Commonwealth Games and the Matildas are our women's soccer team, the name is seen as an extremely patriotic one.
(The "Matilda" in the song "Waltzing Matilda" is the bundle a swagman carries; it isn't about a dancing woman called Matilda).
Matilda Bay is a natural bay on the Swan River in Western Australia, and the Matilda Bay Brewing Company is an Australian brewery, owned by the Foster's Group.