Wikipedia:What "no consensus" means
In any discussion on Wikipedia, there are two possible outcomes: consensus, for some course of action, and no consensus. However, what a "no consensus" result means differs depending on the nature of the discussion. Often, people feel that "no consensus" should mean that the current status quo prevails, which, therefore, defaults to keep. That is not always the case however. Also, just because there is "no consensus" among those participating (a local consensus), does not mean there is no "no consensus" in the broader community. Often it is the case that a closing admin will recognize that arguments for one side are much better founded in (community consensus supported) policy than for the other, and so there actually is consensus support for one particular outcome.
Discussion and debate on a proposal may continue on talk pages after a "no consensus" situation, but in the meantime, it is important that affected articles are not subjected to edit-wars despite a lack of policy or guideline direction on an issue. A status quo approach is preferable where practical and possible to promote article stability and to prevent edit warring.
A no-consensus result at DRV means that no new action will be taken. Deleted content will not be undeleted, although a reasonable request for WP:userfication is usually granted. Undeleted content may be subsequently considered again at XfD, preferably after a few weeks or months, and preferably with the nomination referencing the previous reasons for no consensus. Repeated nominations at DRV are rarely welcomed unless new information is introduced.
Requests for adminship (RfA)
At RfA, if there is no consensus to promote, then the only possibility is that there is no promotion.
In a discussion regarding a section of policy or guideline, "no consensus" means that a proposed section should not be added. If the discussion is about a section already in the policy, that section should be removed. Policy and guideline should reflect consensus. If there is no consensus as to existing policy, then it no longer reflects that and should be removed. Similarly, if there is no consensus over the status of a page (e.g. policy, guideline, essay), then the status may need to be discussed further and more people brought into the discussion.
Blocking and other admin actions
When discussing the appropriateness of a block (or other admin action), a discussion that results in "no consensus" should result in the reversal of that admin action. As with policy, blocks and other admin actions should reflect the consensus of the community. And, while an admin does not need to have a discussion prior to acting in good faith, if a subsequent discussion fails to produce consensus for the action, it should be reversed. 
The following are footnotes:
- If a "consensus" does not mean everyone, then it is some kind of debated vote, with no need to pretend that it is a joint agreement. You don't have someone's consent when they don't. If they disagree, it's not an agreement, period. Just discuss & vote (but don't claim that "we all agree"). Many people have tried to imply that a failed consensus is still a joint agreement, perhaps because Wikipedia policies did not clarify what actions to take when consensus fails. The attitude is like treating a loss of life, as not death, but some other type of life: seek to keep the patient alive, and seek consensus. Replace the word "consensus" using the term "total consent" and the issues become very clear. The plan is not to "overpower" the dissenting opinion with numerous people who agree against them. The plan is to seek consensus, a joint agreement that all can live with. All agree not to "sneak back" and revert the consensus view.