There is a large amount of mis-information out there on this i-Filter.

First some background:

    Adobe has not created a stand alone i-filter for the pdf file type since Acrobat and Reader 7.0.5.
Adobe states that, "iFilter functionality is now bundled within the Acrobat and Reader products. Improvements to iFilter in Acrobat and Reader 8 include support for Vista and Windows Desktop Search, as well as improved performance and stability. It is recommended that you update your copy of Adobe Acrobat or Adobe Reader in order to get the most current iFilter functionality, rather than download and install the stand-alone iFilter plug-in."
In Essence the ONLY reason to look at this i-filter v 6.0 is for posterity... i.e. DON'T BOTHER...
Also a large number of KB articles contain incorrect information with regards to this i-filter:
    Namely KB article #'s 927675, 832809, 928619

Installing Adobe’s iFilter Example

IMPORTANT: Adobe stopped creating a new iFilter as a separate component after version 6.0 (called pdffilt.dll). Many locations on the internet still link to this as the “ONE” to download and install

with SharePoint (found at this location Adobe iFilter 6: http://www.adobe.com/support/downloads/detail.jsp?ftpID=2611). On this site Adobe advises you that the iFilter is now incorporated into, among other things, Acrobat Reader. Currently there is no possibility of extracting and utilizing the current pdf iFilter outside of installing one of Adobe’s Acrobat products on your server (i.e. AcroRdIF.dll and located at C:\Program Files\Adobe\Reader8.0\Reader\AcroRdIF.dll)

The issue is that this iFilter dll is not independent, it requires several others to run correctly which cannot be installed independently of one of Adobe’s Acrobat products.

IMPORTANT: Simply defaulting to Adobe’s older pdffilt.dll is also NOT an option as this will be unable to crawl many documents created with a newer version of Acrobat.

IMPORTANT: Microsoft has several kb articles related to the pdf iFilter (927675, 832809, 928619). As of September 2007 NONE of these will truly fix the problems with the version 8.1 of Adobe’s iFilter, so do NOT bother with them.

First Configure the icon for the new file type, then add this new file type to Indexed file types in SharePoint and then you are ready to install the i-filter as follows: (Note: if you would like help with these first two tasks see the link at the bottom of this article for a pdf file that details everything with indexing new file types).

The Correct way to set up Adobe’s pdf iFilter is as follows (1x per index server):

1. First you must download and install the Acrobat product of choice on your servers. For the purpose of this example we will install Acrobat Reader 8.1. located at http://www.adobe.com/products/acrobat/readstep2.html

2. Add the pdf file extension to the File types crawled by SharePoint:
a. From SharePoint 3.0 Central Administration select <Name of Shared Service Provider> >Search Settings > File Types > New File Type (Add extension pdf here)

3. Modify the following Registry keys by changing their "Default" value to the new CLSID of the Adobe

iFilter: {E8978DA6-047F-4E3D-9C78-CDBE46041603}

    a. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Officeserver\12.0\Search\Setup\ContentIndexCommon\Filters\Extension\.pdf

        set the Default value to {E8978DA6-047F-4E3D-9C78-CDBE46041603}

    b. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0 Search\Setup\ContentIndexCommon\Filters\Extension\.pdf

        set the Default value to {E8978DA6-047F-4E3D-9C78-CDBE46041603}

4. Add the Installation directory of the Adobe Reader v.8.1 to the System Path.

NOTE: This is necessary because the Adobe filter .dll file (AcroRdIF.dll) depends on the AcroRd32.dlland AGM.dll files. These files are located in the Drive_Letter:\Program Files\Adobe\Reader 8.0\Reader folder. Because the Drive_Letter:\Program Files\Adobe\Reader 8.0\Reader path is not included in the system path on the computer that is running SharePoint Server 2007, the SharePoint Server 2007 Search service cannot properly scan the .pdf files.

    a. Click Start, click Control Panel, and then double-click System.

    b. In the System Properties dialog box, click the Advanced tab, and then click Environment Variables.

    c. In the Environment Variables dialog box, double-click Path in the System Variables area.

    d. In the Edit System Variable dialog box, put the cursor at the end of the text in the Variable value box, and then type ;Drive_Letter:\Program Files\Adobe\Reader 8.0\Reader

    e. Click OK three times.

5. Recycle the search service:

    a. net stop oSearch

    b. net start oSearch
and of course you must re-crawl your content (Full Crawl recommended)...

I have excerpted (with permission) a few pages from our SharePoint 2007 Administration course that details all of the items you must accomplish and where to do them in SharePoint to install Adobe's or another i-filter. You may find an excerpt from New Horizons of Minnesota's 5 day SharePoint Administration course here:

I-Filter Configuration.pdf