Last year I had a link about the Gini coefficients for wealth. Go to What has happened to the distribution of wealth in recent years?
To see international data on poverty rates
click on this site from the OECD
To see international data on the distribution of income click on this other site from the OECD
To see the Census Bureau's poverty and income report press release, go to Income, Poverty and Health Insurance Coverage in the United States: 2011
For more Census Bureau data, go to Poverty Data
Below is a graph of some poverty rates over time. The source is Table 2. Poverty Status, by Family Relationship, Race from the Census Bureau.