Adobe has finally released a true 64 bit version of the pdf ifilter. Adobe has successfully tested the filter on the following platforms :

Environment Operating System Application
Desktop Windows XP x64 SP2

* Windows Desktop Search 3 and 4

* Windows Indexing Service

Windows Vista x64 SP1 * Windows Search 4
Server Windows Server 2003 x64 Edition R2 SP2

* Microsoft Office SharePoint Server 2007

* Microsoft Exchange Server 2007

* Windows Desktop Search 3

Windows Server 2008 x64 SP1 * Microsoft Office SharePoint Server 2007
* Microsoft SQL Server 2005
* Windows Search 4

Information - http://blogs.adobe.com/acrobat/2008/12/adobe_pdf_ifilter_9_for_64bit.html

Download - http://www.adobe.com/support/downloads/detail.jsp?ftpID=4025

One of our consultants, Jie Li did some initial benchmarking of the filter alongside the foxit 64-bit ifilter and found the adobe pdf filter to be about 5 times slower than it's Foxit counterpart. You can read about it on Jie's blog. The adobe filter, albeit slow, presents a zero cost solution to those in need of indexing pdf documents on a tight budget.