Rake tesks can be found in:
$RUBY_HOME/lib/ruby/gems/1.8/gems/rails-1.1.2/lib/tasks/
lib/ruby/gems/1.8/gems/rails-1.1.2/lib/tasks> ls -la
total 56
drwxrwx--- 2 4096 2006-08-17 11:46 .
drwxrwx--- 6 4096 2006-07-18 17:50 ..
-rw-rw---- 1 7696 2006-07-18 17:31 databases.rake
-rw-rw---- 1 3921 2006-07-18 17:31 documentation.rake
-rw-rw---- 1 4261 2006-07-18 17:31 framework.rake
-rw-rw---- 1 204 2006-07-18 17:31 log.rake
-rw-rw---- 1 105 2006-07-18 17:31 misc.rake
-rw-rw---- 1 1424 2006-07-18 17:31 pre_namespace_aliases.rake
-rw-rw---- 1 280 2006-07-18 17:31 rails.rb
-rw-rw---- 1 625 2006-07-18 17:31 statistics.rake
-rw-rw---- 1 3176 2006-07-18 17:31 testing.rake
-rw-rw---- 1 770 2006-07-18 17:31 tmp.rake
gernerate,descroyt e.t.c can be found in
vendor/rails/railties/lib/commands/generate.rb