Hey LinkedIn, thanks for not mentioning your Outlook Social Connector plugin - called LinkedIn for Outlook - is for 32bit Office only.
I spent a while trying to install the plugin for my 64bit Outlook 2010. There's no indication on the LinkedIn for Outlook website that there is such a limitation.
I assume it's a too big task to add a few numbers and letters close to the Office version list.
Check the buzz around the 64bit issue from The LinkedIn Blog. As you can see, it took LinkedIn quite a while before answering the related questions.