Personally I have not had a chance to use the data and make apps yet, but I have been following them to find a way to involve in it.
I have seen that more cities are launching Open Data websites. For example, Toronto has toronto.ca/open, and now the City of Edmonton has also launched Open Data Catalogue.
These movements are very important to both citizens and governments. Governments have tremendous amount of data, but often these are closed and not easily accessible. By opening data to public, developers are now able to use that data to make more useful apps and often help governments provide better services.
There are many examples of this, and here are just few: everyblock.com, stumblesafely, fixcity.org, CleanScores.com and among many others.
I would love to explore more of these, and I am very looking forward to seeing more interesting actions to come.