I have an AMD64 system without any i386 multiarch packages. After successfully upgrading to 12.10, aptitude seems to want to install a few, and I can't tell why:

$ sudo aptitude safe-upgrade 
Resolving dependencies...                
The following NEW packages will be installed:
  gcc-4.7-base:i386{a} libarmadillo3{a} libboost-date-time1.49-dev{a} libboost-serialization1.49-dev{a} 
  libboost-serialization1.49.0{a} libboost-thread1.49-dev{a} libboost1.49-dev{a} libc6:i386{a} libgcc1:i386{a} 
  libgdal1{a} libhdf5-7{a} libltdl7:i386{a} libnetcdfc7{a} libodbc1:i386{a} libreadline6:i386{a} 
  libtinfo5:i386{a} odbcinst1debian2:i386{a} unixodbc:i386{a} 

Why libc6:i386, for example? I ask..

$ aptitude why libc6:i386
p   icoutils:i386 Provides icoutils           
p   icoutils:i386 Depends  libc6:i386 (>= 2.8)

... alright, but why icoutils:i386?

$ aptitude why icoutils:i386
p   icoutils:i386 Provides icoutils

But I already have the AMD64 version of icoutils:

$ aptitude search icoutils
i   icoutils                                           - Create and extract MS Windows icons and cursors             
p   icoutils:i386                                      - Create and extract MS Windows icons and cursors 

Has some multiarch behavior changed recently, or am I just overlooking something?

Addendum: Chasing down from gcc-4.7-base:i386, I'm led to qdbus:i386, which is up for installation since it provides qdbus... which I already have.