I usually say "arrow", or "dash-greater-than"... but come to think of it, I very rarely have to ever actually say this.
=> is known as a fat comma or a rocket in Ruby circles.
Rocket makes sense, but fat comma?
In Perl "=>" is (almost) a comma, i.e. { a => 1, b => 2} is the same as { "a", 1, "b" , 2 }. I assume Ruby with its Perl heritage has this to some degree.
<=> is the "spaceship" operator in Perl, Ruby, and Groovy.