I've been sitting on this one for a while since it wasn't very clear that this "Survivor 2299" thing was actually related to Fallout 4. There was a huge amount of speculation that it was and also some evidence showing that it might not be. However, as the days go on, more and more details are emerging that seem to indicate this is a legitimate ARG for an upcoming Fallout 4 reveal.

Again, all of this is merely speculation at this point and may end up just being a huge joke on the Internet and fans of the Fallout series. When you first visit the site you are greeted with a countdown and some morse code. The morse code originally pointed to a date of December 11, 2013. The code has since changed to be a series of letters.
ZL QRNE FVFGRE. V'Z URNQVAT GB GUR VAFGVGHGR. TBQ XABJF JUNG UNCCRARQ GB GUVF CYNPR ABJ. GUVF BYQ ONFGNEQ JVYY URYC HF. UR ZHFG URYC HF. -0321-

A Caesar cipher was used to decipher the message. Translated, it reads...
MY DEAR SISTER. I'M HEADING TO THE INSTITUTE. GOD KNOWS WHAT HAPPENED TO THIS PLACE NOW. THIS OLD BASTARD WILL HELP US. HE MUST HELP US. -321-

The Institute is a location within the Fallout universe. It is the Fallout name for the Massachusetts Institute of Technology. The Institute lies within The Commonwealth and is said to be one of the harshest environments in the Fallout universe.
Irradiated, destroyed, ravaged by raiders and various factions vying for control, it's a brutal place. The one exception to this, however, is The Institute, which is under strict martial law, and which uses sentient, true A.I. androids as slave labor, but which is nonetheless safe for those who are able to get into it.

That's the short of it. Fallout radio personality, Three Dog, also let slip that he's done voice work for the new game back in January. If this is true, expect to begin seeing reveals and announcements in December. And if this is true, get ready because we're shipping up to Boston!

(Information gathered from Observation Deck)