In an unmarked area of the map, a solitary white tower stands on the coast. This tower can be found by swimming round from northern Tirisfal Glades, staying close to the shoreline so as not to induce fatigue. Its purpose is unknown but it has been speculated that it represents an abandoned idea for allowing player to access Quel'Thalas. Another theory is that it is a left over from before Quel'Thalas's current form was conceived. Much of the surrounding terrain bears the hallmarks of a "cookie-cutter" terrain editor fill and it is equally possible that this location is nothing more than the result of a bored developer playing around in an unused area of the game.
If you continue past this tower, you can see that the blood elf starting area is not, in fact, part of the Eastern Kingdoms terrain. (It is not located on the Eastern Kingdoms continent server.) This can be seen in the second image, where the character is swimming in the sea, but her map shows her in the middle of the Ghostlands. Players attempting the reverse of this trick (accessing Tirisfal from the Ghostlands) will find invisible walls blocking their path.
It's worth noting that as of the release of Cataclysm, old world flying allows a more detailed (if distant) look into the unfinished zone. The most notable view is by the portal gate into Ghostlands. Flying as high as you can and as close to the portal as you can (note: this is very limited airspace), will allow you to see a small clearing with two scourge banners planted in the center, as though it were a place of prominence. (Some speculate this is meant to be where Sylvanas Windrunner was slain by Arthas Menethil) A detailed path leads north from this location, further hinting at intended use. Looking West from here, you can see the distinctive spiked wheel roof of a scourge slaughterhouse beyond a mountain. Some now theorize this zone may become another Mount Hyjal, a previously unused area made into a prominent zone.
It has been discovered that mages can access this zone if they possess old world flight. By blinking through a gate in Wetlands located at the southern end of the dwarven farm on the mountainside, mages can mount up on a flyer and fly out of the end of the tunnel, which terminates in a massive empty void beneath the land. By carefully flying north (specifically being careful around the Thandol Span, as flying too high will have you end up in the river, unable to continue) until you fly beneath the portal-gate to Ghostlands and fly out of the ground and into the zone. It is clearly unfinished, as the pathway abruptly sinks into the ground, with the fences sinking with it. Similarly, the aforementioned Scourge Slaughterhouse is sunk up to the roof in the ground. The rest of the zone is an eerily blank expanse, with the signature dark green (almost glowing) grassy ground texture of Ghostlands. From here, you can also access the backdrop of Stratholme, which is a mass of half-finished buildings and the most basic textured scourge Necropolis possible, little more than a grey block with a few rough shapes hacked out of it. Care should be exercised here, as random dismounts can occur.
A similar situation does exist for the draenei islands, but fatigue makes it difficult to test. Mages can climb to southern Darnassus, and mounted slow fall their way to where they should be able to make it to the Exodar, but a wall prevents it. Player death is the usual result.
Originally, Quel'Thalas was intended to be in the game at release, but was eventually postponed. When the first expansion was made, they decided to cut the nation into two zones, and to place it on the Outland continent server, making it easier to restrict access to those who had not purchased the expansion. The same loading screen exists for both the blood elf and draenei zones and Outland. This also causes the minimap arrow for party members in the blood elf or draenei zones to appear on your minimap when you are in Outland (or vice versa).