I'm having a problem with IE8 64 bit and Adobe Reader X when opening embedded PDF's.
If I use the 32 bit IE or any other browser, it opens in the embedded client no problem. But when you attempt to open it via 64bit IE8, big red x.
The two Adobe addons are present in the 32 bit version but not shown at all in the 64 bit version. Attempted multiple reinstalls, restarts, with no luck. Tried adding to safe sites as well.
Adobe Reader X and Adobe Acrobat X are 32-bit applications, and as such they do not install plugins for Internet Explorer x64. They will run happily on a 64-bit operating system but in Windows you must use a 32-bit browser to view PDFs which are flowed into the page using <embed> tags. Direct links to the files will be fine, as they will download and open in the desktop version of Reader if the browser doesn't have an internal handler, but embedded content requires a plugin.
There are no plans for a 64-bit version of Adobe Reader at this time.