Belo Horizonte is home to a 1 line, 19 station metro. Opened in 1986, the 30 km line is still a work in progress. A 10 km, 6 station Line 2 was due to open in 2003. It hasn't happened yet. A third line to the airport, completely underground, is expected to begin construction in late 2012.
Indications are that there is a short subway section on this line. It is yet to be confirmed.
Private Belo Horizonte metro site with links to other Latin American rail sites
Metro workers site
A few photos
CBTU page about new extension
Official Home Page
Station Tour from Skyscraper City where there appears to be a subway section between last stop Vilarinho and next station ESTAÇÃO Waldomiro Lobo.