Although the above-captioned appears on Apple's Support-Downloads website (as of Sep. 17), any attempt to download the update goes to a blank screen with the URL
http://images.apple.com/support/not_found.html .
Attempts at acquiring same from other sources which link to Apple have the same result.
Last night it wouldn't even show up on Software Update; this morning it did. Unfortunately, the disk image file is 144.5 MB. With dial-up access it would take ca 10 hours to download (at ca 4 KB/s), even if one could justify tying up the phone line for that amount of time. (Ergo, non-viable solution.)
Security Update 2014-004 Server (Lion) on the other hand is alive.
Edit: Security Update 2014-004 (Mountain Lion) seems to be functional. Does anybody know what's going on? Apple sure doesn't.