Microsoft recently released SP1 for it's Office Filter Pack 2010.

The filter pack is one of the prerequisites when installing the Hub Transport / Mailbox Server role.

Exchange Search uses the filter pack to:

• Indexing of email attachments on Mailbox Servers
• Scanning of attachments on Hub Transport
• Discovery searches

Since the current update doesn't add, fix of modify any Exchange 2010 functionality, it is not necessary to update existing installations that do not have the update installed.
Nonetheless, it is recommended to start using SP1 for newer installations.

• For more information, check the annoucment here: http://blogs.technet.com/b/exchange/archive/2011/08/02/exchange-server-and-sp1-for-microsoft-office-filter-pack-2010.aspx
• The update can be downloaded here: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=26604