I do not claim to have plumbed the depths of our. However, this seems to be the deal: 'our' variables are package variables, just like $main::foo, except that our makes a LEXICALLY scoped declaration that the variable has been legally imported - basically, you can use it's unqualified package name under use strict.

use strict;
package foo;
our $y  = "This is in package foo"; # $x and $y both package
$foo::x = "This is in package foo"; # variables
print $foo::x;
{ #bare block
    our $x;
    print $x; #$x = $foo::x
} #end of bare block
print $x #Give a warning under use strict
         #because the 'our' declaration
         #is out of scope

package bar;
print $foo::y; #prints $y declared with 'our' in package foo
print $foo::x; #prints $x declared with package name in foo
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I don't know if that helps any, (or just confused) but there it is - the weirdness (and, I think, good use) of our.