The suggested way to get the latest iFilter for PDF's is to install the latest Adobe Reader version 9. However I think that there is a bug in the install process -anyone agree?
The Adobe web site says that the iFilter that comes with Reader version 6,7,8 was the same and that the new iFilter that comes with 9 is an improved version.
My hunch is that the installer for v9 places in the new iFilter, but incorrectly points the file extensions in the registry to the old v6 program, that on a fresh install don't exist.
ie in Regedit - the Gather in Microsoft shared tools should point to
E8978DA6-047F-4E3D-9C78-CDBE46041603, but instead is set up to point to
4C904448-74A9-11D0-AF6E-00C04FD8DC02. (which is iFilter v6)
There appears to be a lot of support on the web for the iFilter v9 not working and people falling back to the v6 one. The Adobe ITMatters blog saying "You may then need to do an additional step of registering that iFilter with SharePoint, but it's easy to do that is not quiet right, as it is not easy.