PROBLEM:
Drupal's block module is limited by the fact that a block can
only have one instance. Each block has a 1:1 relationship with
its region, weight, visibility (and other) settings. This means 
that it is impossible to have blocks in multiple regions or to
have blocks that have different settings on different pages.

SOLUTION:
multiblock module will keep track of multiple instances of blocks
and dispatch to their appropriate block hooks. Using this stratgey,
you would not enable any blocks that are implemented by other
modules. Instead, you will go to admin/build/block/instances and create
an "instance" of a block. Multiblock module will then implement this
block in its own block hook which will forward any block API calls
to the original module's hook. Using this method we can maintain
multiple instances of blocks with different settings but the same
implementation. This should not affect block-level caching. One
catch here is that the configure and save hooks are usually implemented
to save only one set of data. This means that for blocks that are
unaware of multiblock you will only be able to save CUSTOM data (this
doesn't include visibility, weight, region, etc.) for one set of data.

HOW TO USE IT:
1. Go to admin/structure/block/instances
2. Select the type of block you want to create an instance of and
   type a unique title for that instance
3. Click "Add Instance"
4. Go to admin/structure/block
5. Enable the block instance you have just created.

DEVELOPING MULTIBLOCK-ENABLED BLOCKS:
Multiblock should successfully clone any regular block created with the
block API. However, if you clone a regular block that implements a
hook_block_save or hook_block_configure hook, the custom block settings of
one block instance will overwrite the settings of another. To get around
this, you can make a block "multiblock enabled." To do this, you should
add a 'mb_enabled' key with a value of true in hook_block_info to each
multiblock enabled block you are creating. Next, add an optional $edit
argument to your hook_block_view and hook_block_configure functions. Once
you do this, the instances you create will get the block instance ID
passed in the $edit variable for the view, configure, and save $ops. This
will let you save and load different data to different instances based on
this instance ID. It is passed in with the 'multiblock_delta' key with the
following format:
$edit['multiblock_delta'] = array(
          '#type' => 'value',
          '#value' => $block_id
      );

Example implementation of hook_block_info:
function hook_block_info() {
  $blocks['powered-by'] = array(
    'info' => t('Powered by Drupal'),
    'weight' => '10',
    'cache' => DRUPAL_NO_CACHE,
    'mb_enabled' => TRUE,
  );
  return $blocks;
}