US patents are issued on Tuesdays and are published on Thursdays by the USPTO. The USPTO hosts several databases containing patent and related information. Links and brief descriptions are below.
Note: Full text searching for patents here is only available for patents issued form 1976 to the present.
Google Patents claims to provide full-text searching of ALL US patents back to 1790 - but what they actually have done is performed OCR (Optical Character Recognition) on the TIFF files from the USPTO. This works pretty well but be warned that OCR isn't perfect. A mistake in OCR can provide you with incorrect (or even no) results. For older (pre-1976) patents, it is always a good idea to double-check against the original TIFF files. Google Patents can be used to find a patent number, which can then be pulled up directly in the USPTO database, if Google doesn't provide the images directly.
Google Patents includes a classification-grouped search results screen and integration of Prior Art and Google Scholar results. Many of the old Advanced Search options are now available on the results screen.