Adobe has FINALLY released a 64 bit PDF iFilter. For everyone out there running 64 bit MOSS, without a proper 64 bit PDF iFilter, please go get this for yourself. I haven't seen any performance data, but it should increase your indexing performance of PDFs. Details are here. Instructions for installing on MOSS can be found on the linked page.
UPDATE : Some internal testing was done with this Adobe iFilter. The performance still leaves something to be desired. In a head to head comparison, the FoxIT iFilter still runs signicantly faster. The iFilter Blog has some data on this, which can be found here . It's likely that Adobe is continuing to use the 32 bit iFilter and the wrapper from the previous work around.