I have tested two different versions of the "livesearch" macro on two different versions of Confluence and have found the following errors.

Tested on Confluence 2.2.10 and 2.4.2 WAR versions.
Tested livesearch.jar and livesearch-2.4.2jar.

livesearch.jar was found to be strict with syntax:
1. spacekey must be defined otherwise livesearch fails to render with a java.io.IOException
2. cannot specify more than one spacekey, it will break the livesearch macro and return zero results.
3. cannot have multiple instances of the livesearch macro on the same page. Only the first embedded livesearch macro will work, the rest will result in zero search results.

livesearch-2.4.2.jar was found to contain the following bugs:
1. cannot specify more than one spacekey, it will break the livesearch macro and return zero results.
2. cannot have multiple instances of the livesearch macro on the same page. Only the first embedded livesearch macro will work, the rest will result in zero search results.

livesearch-2.4.2.jar allowed usage without defining a spacekey, allowing searching through all spaces. livesearch.jar did not allow this.
livesearch.jar had a ajax script which showed search results in a little popup before the user needs to click on 'go'. livesearh-2.4.2.jar did not have this. Additionally, the ajax box did not appear in Confluence v2.4.2 when using livesearch.jar - refer to screenshot.