Other than Strangers From the Sky and Federation, does any other Trek lit deal with Trek's 21st century? I've always found Trek's depiction of the 21st century facinating. it seems to swing wildly between dark age yet unprecedented space exploration. That Enterprise did not spend much time fleshing out this era was always a bit of a disappointment. While we can all be grateful that Trek's late 20th and early 21st century never came to pass, I think that its unfortunate that the divergence has made it a time period that people have shied away from. In fact, I think that one of the things that diminished my overall enjoyment of First Contact was that it obliterated the well though out timeline created in Federation. The steady decline of civilization coupled with expanding space exploration depecited in that book fit with what we knew about that era better than what we ultimately got in First Contact.
It didn't obliterate anything; the book is still there for you to read and enjoy. It just offered an alternative view. That view may be more binding on subsequent canonical works, but it's not as if one fictional version of the future is somehow more real than another fictional version of the future. It's good to have alternatives. The Lost Era: The Sundered covers the mid-21st century rather well, dealing with the backstory behind WWIII, the recovery, and the development of warp drive. There's also a story in Strange New Worlds 09, "The Immortality Blues," that depicts WWIII from the immortal Flint's POV, in a manner consistent with The Sundered.
There's also a Strange New World story featuring a meeting between Zefram Cochrane and Mestral before WWIII. I haven't read yet, though.
David Gerrold's The Galactic Whirlpool also presents a rather extensive history of the that time period while presenting the history of the derelict ship.