comScore has released their usual web rankings for the April 2008 period.
Brazil is still at the top with 19.3 Million users, Mexico and Argentina follow.
Here is the full chart:

The report gives a very complete picture of the Internet landscape in the region. Usage per country, top websites and other data.
Check the press release here:
comScore Releases Top Latin America Web Rankings for April 2008 [Comscore]
