I think that, although the same length, this is different to the typographic copyright, which I think applies only to that particular layout.
The 25 year copyright on publishing unpublished public domain works is a copyright on the works, not the layout. (... "protection equivalent to the economic rights of the author.")
Of course, this won't become important (in the UK) until 2015, when the 25-year term will start to exceed the term under the transitional arrangements which give copyright until 2040 anyway.
You would have though that, for something so essentially simple, copyright laws would be a lot less complex!
Originally Posted by HarryT
It's not entirely odd, because the same 25 year copyright term applies to someone who applies a non-trivial layout to a public domain work; that particular "arrangement" of the work has a copyright term of 25 years from the date of publication; it's called a "typographical copyright".