While the front splash page for Change.gov has linked to the main White House website for years, until recently, you could still continue on to see the materials and agenda laid out by the administration. This was a particularly helpful resource for those looking to compare Obama's performance in office against his vision for reform, laid out in detail on Change.gov.
Why the change?
Here's one possibility, from the administration's ethics agenda:
Protect Whistleblowers: Often the best source of information about waste, fraud, and abuse in government is an existing government employee committed to public integrity and willing to speak out. Such acts of courage and patriotism, which can sometimes save lives and often save taxpayer dollars, should be encouraged rather than stifled. We need to empower federal employees as watchdogs of wrongdoing and partners in performance. Barack Obama will strengthen whistleblower laws to protect federal workers who expose waste, fraud, and abuse of authority in government. Obama will ensure that federal agencies expedite the process for reviewing whistleblower claims and whistleblowers have full access to courts and due process.
It may be that Obama's description of the importance of whistleblowers went from being an artifact of his campaign to a political liability. It wouldn't be the first time administration positions disappear from the internet when they become inconvenient descriptions of their assurances.
Obama's vision for lobbying transparency has similarly been discarded along the way, but the timing here suggests that the heat on Obama's whistleblower prosecutions has led the administration to unceremoniously remove their previous positions.
Update, 7/30/2013: Change.gov is now back up.