GPG/PGP Verification of Revocation

How does one verify a key revocation?

After revoking a key and sending the revocation to MIT's keyserver, I noticed that the key is listed as such:

pub  2048R/XXXXXXXX 2011-01-01 *** KEY REVOKED *** [not verified]


Who is responsible for the 'verification of the revocation'? Does the owner of the key do this verification? If so, how is this accomplished? Do other people sign the revocation and at a certain point it becomes verified?

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I don't get this note either, but I do notice that all of the revoked keys I've seen on MIT's keyserver have this. –  gertvdijk Apr 23 '13 at 0:10