Some minor nitpicking:
– Blocks are anonymous functions.
– Usually the alternative delimiters to do…end are called “curly braces” or “curly brackets” – “brackets” are (…) if I’m not mistaken.
– There is another, older and thus potentially more compatible syntax to create lambdas: lambda {|arg| …} and lambda do |arg| … end

For those who want to dig into a few other aspects my old articles are still online:
http://blog.rubybestpractices.com/posts/rklemme/001-Using_blocks_for_Robustness.html
http://blog.rubybestpractices.com/posts/rklemme/002_Writing_Block_Methods.html