The presumably last update to InDesign CS5.5 has been released through Adobe Application Manager updates (choose Help > Updates if you don’t receive them automatically).

John Hawkinson created a comprehensive post about it at Adobe InDesign Forums with a list of bug fixes.

Among the bugs fixed that he highlighted are:

Import/Export: Wrong page number on export book to PDF

Print/PDF: InDesign hangs or quits unexpectedly during certain package and preflight operations.

But there are many more fixes, so you should download the update.