Installing GI 11.2.0.1 on OL6 under VBox. This is something I've done scores (if not hundreds) of times with no such issue. Prereq check returns this:

Before you jump to conclusions, yes I installed the pre-install package:
[root@vblnx6gi11 ~]# yum install oracle-rdbms-server-11gR2-preinstall
Loaded plugins: security, ulninfo
Setting up Install Process
Resolving Dependencies
<snip a lot of output, but trust me it completed with no problems>
And just to put the frosting on the cake, when OUI got to this point I opened a second session as root and addressed each listed package in turn:
[root@vblnx6gi11 ~]# yum -y install libaio
Loaded plugins: security, ulninfo
Setting up Install Process
public_ol6_UEKR3_latest | 1.2 kB 00:00
public_ol6_latest | 1.4 kB 00:00
Package libaio-0.3.107-10.el6.x86_64 already installed and latest version
Nothing to do
[root@vblnx6gi11 ~]# yum -y install glibc
Loaded plugins: security, ulninfo
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package glibc.x86_64 0:2.12-1.166.el6 will be updated
--> Processing Dependency: glibc = 2.12-1.166.el6 for package: glibc-common-2.12-1.166.el6.x86_64
--> Processing Dependency: glibc = 2.12-1.166.el6 for package: glibc-devel-2.12-1.166.el6.x86_64
--> Processing Dependency: glibc = 2.12-1.166.el6 for package: glibc-headers-2.12-1.166.el6.x86_64
---> Package glibc.x86_64 0:2.12-1.192.el6 will be an update
--> Running transaction check
---> Package glibc-common.x86_64 0:2.12-1.166.el6 will be updated
---> Package glibc-common.x86_64 0:2.12-1.192.el6 will be an update
--> Processing Dependency: tzdata >= 2015g-4 for package: glibc-common-2.12-1.192.el6.x86_64
---> Package glibc-devel.x86_64 0:2.12-1.166.el6 will be updated
---> Package glibc-devel.x86_64 0:2.12-1.192.el6 will be an update
---> Package glibc-headers.x86_64 0:2.12-1.166.el6 will be updated
---> Package glibc-headers.x86_64 0:2.12-1.192.el6 will be an update
--> Running transaction check
---> Package tzdata.noarch 0:2015e-1.el6 will be updated
---> Package tzdata.noarch 0:2016d-1.el6 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
And so on, down the list. As you can see, some mixed results right there, but in the end, even after a restart, prereq check failed, and with the same list as before.
Looking at it a bit more closely, it looks like the 'missing' packages are all 32-bit, as the same names appear in the output of 'yum list installed', but with '.x86_64' appended to the names. If this is the case, what's up with that?
The downloaded zip file from which I extracted the installation, freshly downloaded from OTN downloads, is 'linux.x64_11gR2_grid.zip', Clearly the 64-bit version.