I made a panoptic results list. It may help you understand what was
changed by my patch.

The following long list is a result of this tester.
http://gist.github.com/173478

Note that 1.9.2' means the patched ruby.
-----------------------------------
# '{}' in four rubies

## in 1.9.2'
{}
## in 1.9.1
{}
## in 1.8.7
{}
## in 1.8.6
{}

# '{1 => 2}' in four rubies

## in 1.9.2'
{1=>2}
## in 1.9.1
{1=>2}
## in 1.8.7
{1=>2}
## in 1.8.6
{1=>2}

# '{1}' in four rubies

## in 1.9.2'
#<Proc:0x2d9d58@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected '}', expecting tASSOC
p({1})
     ^
## in 1.8.7
-e:1: odd number list for Hash
p({1})
     ^
## in 1.8.6
-e:1: odd number list for Hash
p({1})
     ^

# '{|x| 1 }' in four rubies

## in 1.9.2'
#<Proc:0x2d9d08@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected '|', expecting '}'
p({|x| 1 })
    ^
-e:1: syntax error, unexpected '}', expecting $end
p({|x| 1 })
          ^
## in 1.8.7
-e:1: syntax error, unexpected '|', expecting '}'
p({|x| 1 })
    ^
-e:1: syntax error, unexpected '}', expecting $end
p({|x| 1 })
          ^
## in 1.8.6
-e:1: syntax error, unexpected '|', expecting '}'
p({|x| 1 })
    ^
-e:1: syntax error, unexpected '}', expecting $end
p({|x| 1 })
          ^

# '{ p 1 => 2 }' in four rubies

## in 1.9.2'
#<Proc:0x2d9ce0@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected tINTEGER, expecting keyword_do or '{' or '('
p({ p 1 => 2 })
       ^
## in 1.8.7
-e:1: syntax error, unexpected tINTEGER, expecting kDO or '{' or '('
p({ p 1 => 2 })
       ^
## in 1.8.6
-e:1: syntax error, unexpected tINTEGER, expecting kDO or '{' or '('
p({ p 1 => 2 })
       ^

# '{ p(1) => 2 }' in four rubies

## in 1.9.2'
1
{1=>2}
## in 1.9.1
1
{1=>2}
## in 1.8.7
1
{nil=>2}
## in 1.8.6
1
{nil=>2}

# '{ p(1 => 2) }' in four rubies

## in 1.9.2'
#<Proc:0x2d9ce0@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected '}', expecting tASSOC
p({ p(1 => 2) })
               ^
## in 1.8.7
-e:1: odd number list for Hash
p({ p(1 => 2) })
               ^
## in 1.8.6
-e:1: odd number list for Hash
p({ p(1 => 2) })
               ^

# '{ p {} => {} }' in four rubies

## in 1.9.2'
{nil=>{}}
## in 1.9.1
{nil=>{}}
## in 1.8.7
{nil=>{}}
## in 1.8.6
{nil=>{}}

# '{p:p}' in four rubies

## in 1.9.2'
{:p=>nil}
## in 1.9.1
{:p=>nil}
## in 1.8.7
-e:1: syntax error, unexpected tSYMBEG, expecting kDO or '{' or '('
p({p:p})
     ^
## in 1.8.6
-e:1: syntax error, unexpected tSYMBEG, expecting kDO or '{' or '('
p({p:p})
     ^

# '{ p, p = 1, 2, 3 }' in four rubies

## in 1.9.2'
#<Proc:0x2d9c54@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected ',', expecting tASSOC
p({ p, p = 1, 2, 3 })
      ^
-e:1: syntax error, unexpected '}', expecting $end
p({ p, p = 1, 2, 3 })
                    ^
## in 1.8.7
{nil=>1, 2=>3}
## in 1.8.6
{nil=>1, 2=>3}

# 'p { 1 }' in four rubies

## in 1.9.2'
nil
## in 1.9.1
nil
## in 1.8.7
nil
## in 1.8.6
nil

# 'p({ 1 })' in four rubies

## in 1.9.2'
#<Proc:0x2d9d30@-e:1>
#<Proc:0x2d9d30@-e:1>
## in 1.9.1
-e:1: syntax error, unexpected '}', expecting tASSOC
p(p({ 1 }))
         ^
## in 1.8.7
-e:1: odd number list for Hash
p(p({ 1 }))
         ^
## in 1.8.6
-e:1: odd number list for Hash
p(p({ 1 }))
         ^