On my 11.10 x86_64:

Package `flashplugin-downloader' is not installed.                                                                                                                                                                                         
Use dpkg --info (= dpkg-deb --info) to examine archive files,                                                                                                                                                                              
and dpkg --contents (= dpkg-deb --contents) to list their contents.                                                                                                                                                                        
Package `ia32-libs-multiarch' is not installed.                                                                                                                                                                                            
Use dpkg --info (= dpkg-deb --info) to examine archive files,                                                                                                                                                                              
and dpkg --contents (= dpkg-deb --contents) to list their contents.                                                                                                                                                                        
Package `nspluginviewer' is not installed.                                                                                                                                                                                                 
Use dpkg --info (= dpkg-deb --info) to examine archive files,                                                                                                                                                                              
and dpkg --contents (= dpkg-deb --contents) to list their contents.                                                                                                                                                                        
Package `qdbus' is not installed.                                                                                                                                                                                                          
Use dpkg --info (= dpkg-deb --info) to examine archive files,                                                                                                                                                                              
and dpkg --contents (= dpkg-deb --contents) to list their contents.

I'd say that this affects i386 packages on x86_64:

$ dpkg-query --list flashplugin-downloader qdbus
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                                 Version                                              Description
+++-====================================================-====================================================-========================================================================================================================
un  flashplugin-downloader                               <none>                                               (no description available)
un  qdbus                                                <none>                                               (no description available)

 dpkg-query --list flashplugin-downloader:i386 qdbus:i386
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                                                 Version                                              Description
+++-====================================================-====================================================-========================================================================================================================
ii  flashplugin-downloader:i386                          11.0.1.152ubuntu1                                    Adobe Flash Player plugin downloader
ii  qdbus:i386                                           4:4.7.4-0ubuntu8                                     Qt 4 Dbus Tool

Probably only i386 packages without an x86_64 equivalent installed.