  The Mock LISA Data Challenges are a program to demonstrate LISA data-analysis
capabilities and to encourage their development. Each round of challenges
consists of several data sets containing simulated instrument noise and
gravitational-wave sources of undisclosed parameters. Participants are asked to
analyze the data sets and report the maximum information about source
parameters. The challenges are being released in rounds of increasing
complexity and realism: in this proceeding we present the results of Challenge
2, issued in January 2007, which successfully demonstrated the recovery of
signals from supermassive black-hole binaries, from ~20,000 overlapping
Galactic white-dwarf binaries, and from the extreme-mass-ratio inspirals of
compact objects into central galactic black holes.
