Correct. It is wonderful sugar, but somewhat limiting. Realistically, you need to know both syntaxes.

  irb(main):001:0> hash={:"symbol with space" => nil}
  => {:"symbol with space"=>nil}
  irb(main):002:0> hash={"symbol with space": nil}
  SyntaxError: (irb):2: syntax error, unexpected ':',  expecting tASSOC
  hash={"symbol with space": nil}
                          ^
	from /usr/bin/irb1.9.1:12:in `<main>'
  irb(main):003:0> hash={"symbolwithoutspace": nil}
  SyntaxError: (irb):3: syntax error, unexpected ':',  expecting tASSOC
  hash={"symbolwithoutspace": nil}
                           ^
	from /usr/bin/irb1.9.1:12:in `<main>'
  irb(main):004:0> hash={symbolwithoutspace: nil}
  => {:symbolwithoutspace=>nil}
  irb(main):005:0> hash={symbol with space: nil}
  SyntaxError: (irb):5: syntax error, unexpected tIDENTIFIER, expecting keyword_do or '{' or '('
  hash={symbol with space: nil}