Yes. As long you aren't using Ruby 1.8, you can use {a: 'b'} syntax. It does exactly what {:a => 'b'} does, it's just shorter.
When ran in IRB, both examples show identical results (in Ruby 1.9).
$ irb1.9
irb(main):001:0> {:a => 'b'}
=> {:a=>"b"}
irb(main):002:0> {a: 'b'}
=> {:a=>"b"}
irb(main):003:0>
But when running in Ruby 1.8, {a: 'b'} doesn't work.
$ irb1.8
irb(main):001:0> {:a => 'b'}
=> {:a=>"b"}
irb(main):002:0> {a: 'b'}
SyntaxError: compile error
(irb):2: odd number list for Hash
{a: 'b'}
   ^
(irb):2: syntax error, unexpected ':', expecting '}'
{a: 'b'}
   ^
(irb):2: syntax error, unexpected '}', expecting $end
        from (irb):2
irb(main):003:0>