This is how you find out what kernel yum thinks you are running:

{{{
  import yum
  from rpmUtils.transaction import initReadOnlyTransaction

  ts = initReadOnlyTransaction()
  print yum.misc.get_running_kernel_pkgtup(ts)
}}}

...or, with less imports and more yum:

{{{
  import yum

  yb = yum.YumBase()
  ts = yb.rpmdb.readOnlyTS()
  print yum.misc.get_running_kernel_pkgtup(ts)
}}}