I see you're not using mingw32-wine-mono or mingw64-wine-mono binary package names but put the .msi file in a binary rpm named mingw-wine-mono. Is this intentional? Does it contain both the win32 and win64 pieces?

Yes this is intentional. I'd prefer a setup like wine-gecko but this is what wine currently supports. 

Here is the quote from: http://wiki.winehq.org/Mono
"Unlike gecko, there is only one package containing the code for both x86 and x86_64, as most of the code does not depend on the architecture."

http://fedora.lowlatency.de/review/mingw-wine-mono.spec
http://fedora.lowlatency.de/review/mingw-wine-mono-0.0.4-5.fc17.src.rpm

https://koji.fedoraproject.org/koji/taskinfo?taskID=4201110

* Wed Jun 27 2012 Andreas Bierfert <andreas.bierfert[AT]lowlatency.de>
- 0.0.4-5
- add conditional so package builds on x86-64 builders as well

Regarding the naming issue that Erik pointed out:

The MinGW Packaging Guidelines are for library packages that can be used for building Windows apps. But this package is different; it only installs a .msi and no dlls / header files and is apparently only meant for use within Wine.

As such, perhaps it would be clearer if it's called 'wine-mono'? This package is really just another component for the wine stack, even though it's built using the mingw cross compiler. I don't think the mingw naming guidelines are applicable here.

I am fine with it either way. However, if we decide on wine-mono we should rename the gecko stuff accordingly...

I was just about to propose the exact same thing about the package naming :)
I'm +1 to use the package name wine-mono given the situation

http://fedora.lowlatency.de/review/wine-mono.spec
http://fedora.lowlatency.de/review/wine-mono-0.0.4-6.fc17.src.rpm

* Fri Jun 29 2012 Andreas Bierfert <andreas.bierfert[AT]lowlatency.de>
- 0.0.4-6
- rename to wine-mono

Taking for review.

Even though you are not packaging a traditional MinGW package, you are using the MinGW toolkit to build it so I feel it should try to follow the MinGW packaging guidelines.

$ md5sum Downloads/wine-mono-0.0.4.tar.gz 
61c5ee49b8847c4dccfdab1fbc0706ae  Downloads/wine-mono-0.0.4.tar.gz
$ md5sum rpmbuild/SOURCES/wine-mono-0.0.4.tar.gz 
61c5ee49b8847c4dccfdab1fbc0706ae  rpmbuild/SOURCES/wine-mono-0.0.4.tar.gz

$ rpmlint rpmbuild/SPECS/wine-mono.spec 
0 packages and 1 specfiles checked; 0 errors, 0 warnings.
$ rpmlint Downloads/wine-mono-0.0.4-6.fc17.src.rpm 
1 packages and 0 specfiles checked; 0 errors, 0 warnings.
$ rpmlint /home/michael/rpmbuild/RPMS/noarch/wine-mono-0.0.4-6.fc17.noarch.rpm
wine-mono.noarch: E: incorrect-fsf-address /usr/share/doc/wine-mono-0.0.4/mono-COPYING.LIB
wine-mono.noarch: E: incorrect-fsf-address /usr/share/doc/wine-mono-0.0.4/mono-mcs-LICENSE.GPL
wine-mono.noarch: E: incorrect-fsf-address /usr/share/doc/wine-mono-0.0.4/mono-mcs-LICENSE.LGPL
1 packages and 0 specfiles checked; 3 errors, 0 warnings.

+ OK
! Needs to be looked into
/ Not applicable

[+] Compliant with generic Fedora Packaging Guidelines
[/] Source package name is prefixed with 'mingw-'
[!] Spec file starts with %{?mingw_package_header}
[!] BuildRequires: mingw32-filesystem >= 95 is in the .spec file
[!] BuildRequires: mingw64-filesystem >= 95 is in the .spec file
[/] Spec file contains %package sections for both mingw32 and mingw64 packages
[+] Binary mingw32 and mingw64 packages are noarch
[/] Spec file contains %{?mingw_debug_package} after the %description section
[/] Uses one of the macros %mingw_configure, %mingw_cmake, or %mingw_cmake_kde4
    to configure the package
[/] Uses the macro %mingw_make to build the package
[/] Uses the macro %mingw_make to install the package
[/] If package contains translations, the %mingw_find_lang macro must be used
[/] No binary package named mingw-$pkgname is generated
[/] Libtool .la files are not bundled
[/] .def files are not bundled
[/] Man pages which duplicate native package are not bundled
[/] Info files which duplicate native package are not bundled
[/] Provides of the binary mingw32 and mingw64 packages are equal
[/] Requires of the binary mingw32 and mingw64 packages are equal

The incorrect-fsf-address rpmlint warning should be reported upstream.

Please check the items I marked that need looking into before I pass the review:
-%?mingw_package_header should be %{?mingw_package_header}
-The BRs for the filesystem packages are missing.

incorrect-fsf-address reported upstream: http://bugs.winehq.org/show_bug.cgi?id=31121

http://fedora.lowlatency.de/review/wine-mono.spec
http://fedora.lowlatency.de/review/wine-mono-0.0.4-7.fc17.src.rpm

* Wed Jul 04 2012 Andreas Bierfert <andreas.bierfert[AT]lowlatency.de>
- 0.0.4-7
- add mingw-filesystem BR
- fix header macro

Looks good.

================================================
 The package wine-mono is APPROVED by mooninite
================================================

New Package SCM Request
=======================
Package Name: wine-mono
Short Description: Mono library required for Wine
Owners: awjb
Branches: f17

Git done (by process-git-requests).

Thanks for the review!