Hilton has quietly changed the requirements for (re)qualifying for Gold and Diamond status in 2013. This has been buried in the terms and conditions of the program.
Requirement for Hilton HHonors Gold Status
The current requirement has been 16 stays, 36 nights, or 60K base points. In 2013, you need 20 stays, 40 nights, or 75K base points.
Requirement for Hilton HHonors Diamond Status
The current requirement is 28 stays, 60 nights, or 100K base points. In 2013, the new requirement is 30 stays, 60 nights, or 120K base points.
It is interesting that Hilton is making qualifying for Gold or Diamond status more difficult, if you are actually staying at their hotels.
You can get Gold status very easily through fast track offer or having a correct credit card. You can also earn Diamond status by charging enough on your Hilton branded card.