"The Black Balloon" is an Australian drama about the family and school life of a teenage boy called Thomas who has a severely autistic older brother called Charlie, a heavily-pregnant mother (played by Toni Collette, brilliantly as always), and a rather weird Army father who seems to inexplicably communicate via a teddy bear called Rex some of the time. At the start of the film the family has moved to a new house, so Thomas has the challenge of a new school in addition to this.
Most of the plot concerns his developing relationship with Jackie, a girl from school, and with him coming to terms with his brother's condition and how badly it impacts the whole family, particularly once his mother has to go into hospital on bedrest as a result of her pregnancy (Charlie requires constant supervision or poo-smearing etc is the result...). As other reviewers have said, there are pretty strong similarities to "What's Eating Gilbert Grape", but it is by no means a carbon copy (the protagonist in this film is a great deal younger than Gilbert, for a start, and whereas Gilbert's father is dead and mother isn't physically able to look after Arnie, in this movie the parents actually do the bulk of the caring, which I felt shifted the focus enough to make it distinct).
I really enjoyed the film, and felt that it was probably a pretty realistic depiction of what a young man in that family setting would go through (slightly unrealistic romance with perfect girl notwithstanding!). It was funny in parts, sad in others, and generally met my expectations of an Australian film (I like Australian films. A lot. "Amy" starring Rachel Griffiths is another very good one, as is "Cosi" with Toni Collette, although I'm not sure either are available in this country). Recommended.