My $0.02:

I feel that the arrow syntax yielding a standalone Proc (my_proc = ->(x) 
{ .. }) is distinctly out of place compared to existing Ruby syntax. I 
would give my support to turning lambda into a keyword, with the syntax 
(my_proc = lambda(x) { ... }) for the simple reason that it is 
reminiscent of method call syntax with an accompanying block (for 
example open("blah") { |f| ... }).