As the agency explained it (emphasis added):

Any invention that is new, useful, non-obvious, and which is accompanied by a written description disclosing how to make and use it can be patented. Applicants’ submissions enjoy a presumption of patentability. Thus, to reject an application the USPTO is responsible for ensuring that any evidence indicating that the invention is not new or is obvious (known as “prior art”) is identified and explaining why the invention is not patentable in view of the evidence.

Applicants have a duty to disclose to the USPTO relevant prior art of which they are aware. However, applicants are not required to search for prior art. Under the USPTO’s accelerated examination procedure, applicants will be required to conduct a search of the prior art, to submit all prior art that is closest to their invention, and explain what the prior art teaches and how their invention is different.

In addition to providing and explaining any prior art references, applicants must explicitly state how their invention is useful and must show how the written description supports the claimed invention. The proposal also limits the number of claims allowed in each application and shortens the time periods for responding to most USPTO communications.

The accelerated examination procedure is designed to give applicants quality patents in less time. In exchange for quick examination, patent examiners will receive more focused and detailed information about the invention and the closest prior art from the applicants. This increased disclosure upfront by applicants will help examiners more quickly make the correct decision about whether a claimed invention deserves a patent.

Here is the more formal Federal Register version (and an annotated Word version, more useful), which notes that this program begins August 25, 2006, and applies to make special applications as well.

To participate, the entire process is online: the application and replies must be filed using the USPTO's electronic filing system (EFS). The applicant must agree to phone interviews to expedite the process. A written office action is the kiss of death, to which a reply must be made within a month; no time extensions permitted.

Applications are limited to 20 claims, three or fewer independent, with no multiple dependent claims. Argument for patentability can only go to independent claims, including through appeal. Strict restriction requirements apply, so declare your own divisionals.

The prior art search must include "patents and patent application publications, foreign patent documents, and non-patent literature," unless you can justify a thinner search "with reasonable certainty" (don't bet the ranch on that; just do the search). The search "must also encompass the disclosed features that may be claimed." A detailed analysis of the prior art must accompany the application..

Any claim amendments have to be in the specific areas previously analyzed, or an updated support document must be filed. In other words, adding claim limitations is a big deal.

FYI, Patent Hawk provides the services necessary to benefit from accelerated examination.