Public access to UAS (aka UFO) files can made through the Defence Force Library at Defence House, Wellington.
The documents are available for consultation in the library (but not for loan). Photocopying facilities are at the OIA rates -: first 20 pages, gratis, thereafter 20 cents per page.
Please contact the library in advance of your visit by telephoning 64 4 496 0842.
Further information and many interesting images from the files can be found on the Stuff.co.nz website
Some public libraries also hold copies of these documents.
Update: 31 March 2011
A second release of UAS files is available for consultation in the Defence Force Library. The additional three volumes (approx 400 pages) range from the period March 2009 to the current date. Public access can be arranged as above.