I can review this later today

naming: NOT ok, since this package is to replace qxmpp, per
http://fedoraproject.org/wiki/Packaging/Guidelines#Renaming.2FReplacing_Existing_Packages
1. Must add (something like)
Obsoletes: qxmpp-dev < 0.7.3
Provides:  qxmpp-dev = %{version}-%{release}
and to -devel subpkg,
Obsoletes: qxmpp-dev-devel < 0.7.3
Provides:  qxmpp-dev-devel = %{version}-%{release}

sources: ok
5badeba0db3d87e4d56ac8ac6da71fda  qxmpp-0.7.3.tar.gz

2. SHOULD drop not needed or used
Group:
tags

scriptlets: ok

macros: ok

3. SHOULD create/use upstreamable patch instead of this .spec hack:
%if "%{_lib}" == "lib64"
%__mv ${RPM_BUILD_ROOT}/usr/{lib,lib64}
%endif

4. MUST move these from -devel to main pkg:
%doc AUTHORS CHANGELOG LICENSE.LGPL README

Fixed.

SPEC: https://raw.github.com/Ignotus/fedora-packages/7f885cfd379816a1db1b69993cd198254aee21cd/qxmpp/qxmpp.spec
SRPM: https://dl.dropbox.com/s/gy3egkzmyn3tirq/qxmpp-0.7.3-2.fc17.src.rpm?dl=1

I'd recommend you keep the Obsoletes static
Obsoletes: qxmpp-dev-devel < 0.7.3
and not use %{version} here.

otherwise, APPROVED.

Once imported, built, you'll want to follow the package end of life procedure for qxmpp-dev,
http://fedoraproject.org/wiki/How_to_remove_a_package_at_end_of_life

Please fill in the SCM request form in a comment when setting the fedora-cvs flag, otherwise the admins (or rather their scripts) will not be able to process your requests.

New Package SCM Request
=======================
Package Name: qxmpp
Short Description: Qt XMPP Library
Owners: ignotusp
Branches: f16 f17 f18
InitialCC:

Git done (by process-git-requests).

qxmpp-0.7.3-2.fc16 has been submitted as an update for Fedora 16.
https://admin.fedoraproject.org/updates/qxmpp-0.7.3-2.fc16

qxmpp-0.7.3-2.fc17 has been submitted as an update for Fedora 17.
https://admin.fedoraproject.org/updates/qxmpp-0.7.3-2.fc17

qxmpp-0.7.3-2.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/qxmpp-0.7.3-2.fc18

Package qxmpp-0.7.3-2.fc17:
* should fix your issue,
* was pushed to the Fedora 17 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing qxmpp-0.7.3-2.fc17'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2012-14949/qxmpp-0.7.3-2.fc17
then log in and leave karma (feedback).

qxmpp-0.7.3-4.git95a225b.fc16 has been submitted as an update for Fedora 16.
https://admin.fedoraproject.org/updates/qxmpp-0.7.3-4.git95a225b.fc16

qxmpp-0.7.4-1.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/qxmpp-0.7.4-1.fc18

qxmpp-0.7.4-1.fc18 has been pushed to the Fedora 18 stable repository.  If problems still persist, please make note of it in this bug report.

qxmpp-0.7.5-1.fc17 has been submitted as an update for Fedora 17.
https://admin.fedoraproject.org/updates/qxmpp-0.7.5-1.fc17

dependency problems when installing leechcraft-full.0.5.80-1.fc18.x86_64:
>
>
Running transaction check
---> Package leechcraft-azoth.x86_64 0:0.5.80-1.fc18 will be installed
--> Processing Dependency: libqxmpp-dev.so.0()(64bit) for package: leechcraft-azoth-0.5.80-1.fc18.x86_64
Package qxmpp-dev-0.6.3.1-1.fc18.x86_64 is obsoleted by qxmpp-0.7.4-1.fc18.x86_64 which is already installed
---> Package qscintilla.x86_64 0:2.6.2-3.fc18 will be installed
---> Package rb_libtorrent.x86_64 0:0.16.4-1.fc18 will be installed
--> Processing Dependency: libGeoIP.so.1()(64bit) for package: rb_libtorrent-0.16.4-1.fc18.x86_64
--> Running transaction check
---> Package GeoIP.x86_64 0:1.4.8-4.fc18 will be installed
---> Package leechcraft-azoth.x86_64 0:0.5.80-1.fc18 will be installed
--> Processing Dependency: libqxmpp-dev.so.0()(64bit) for package: leechcraft-azoth-0.5.80-1.fc18.x86_64
Package qxmpp-dev-0.6.3.1-1.fc18.x86_64 is obsoleted by qxmpp-0.7.4-1.fc18.x86_64 which is already installed
--> Finished Dependency Resolution
Error: Package: leechcraft-azoth-0.5.80-1.fc18.x86_64 (fedora)
           Requires: libqxmpp-dev.so.0()(64bit)
           Available: qxmpp-dev-0.6.3.1-1.fc18.x86_64 (fedora)
               libqxmpp-dev.so.0()(64bit)

Are you from the leechcraft.ru ?