So every set the same thing happens: spoilers are released, cards are quickly found that are the "hallmark" cards of the set (Scuta and Doomsday Specter in Planeshift) and everyone goes crazy trying to secure four copies of them. This makes for great trading, but it misses something - truly great players scan the lands and artifacts first. The issue is that these cards are the easiest to break, because they lack any color affiliation. So inevitably a month or so after the release of a set, one land or artifact becomes the "must-have" sleeper of the set. In Visions it was Quicksand, in Fourth Edition it was Mishra's Factory and Strip Mine (although everyone knew that was good). In Masques it was the accursed Port.
This brings up another point: Sometimes gremlins must hijack R&D when the lands are being tested. Look through the past sets, and you will quickly notice no other type of card (Instants, Sorceries, and so on) consistently has a bigger gap in power between the best and worst cards. Some lands are RIDICULOUSLY powerful. Library and Academy are among the worst (or best, depending on your point of view) cards in the game - these must have been made the night the drunk gremlins were making cards. These two cards are simply way too good. Land has no casting cost or color requirement, so it is hard to penalize someone for laying land; and as a result, most lands have the same casting cost. (Unlike, say, comparing Hornet Cobra from Legends - 1GG, 2/1, First Strike - with Elvish Archer: 1G, 2/1, First Strike.) (Well, there are "comes into play tapped" and sacrifice effects, but generally you're right -- The Ferrett)
On the other end of the spectrum are the HORRIBLE lands, lands so bad that the mere mention of them sends veterans in to giggles, cards that are never going to see the light of a trade binder, let alone the sleeve of a tournament deck. I like to think of these lands as "proxies to be." Among the most wretched "proxies to be" are Sorrow's Path (Oh... my... God! This CARD SUCKS), the Homelands Filter lands and the Urza lands. Imagine, a Sorrow's Path or a Library of Alexandria: They both use up a land drop and nothing else, they're both the same rarity, and yet one is so much better than the other that I cannot think of a way to adequately describe the difference. Its like winning a sweepstakes and being offered a Rolls Royce or a Razor Scooter. It's a no-brainer.
But on a rare occasion WotC gets it right (this gremlin is called "Mark Rosewater"). The land is dead-on balanced. The fact that it is a non-basic land makes it somewhat of a questionable choice, but its ability makes it worthwhile. This is the perfect tournament card. One that goes in a lot of decks, but not EVERY deck. Quicksand and Reflecting Pool were like this... And now we can add a new staple tournament land to the list. It is a card that has gotten very little press, yet it is one of the most useful cards in Planeshift.
The card is Terminal Moraine.
At first glance, it may seem a little underpowered - after all, didn't Glaciers do the exact same thing? And it did it over and over again. But this thinking is flawed. One cannot compare old cards with new cards. Clearly, Necro is better than Bargain (although they are not openly comparable), but Bargain was a good card in its own right. The metagame was different enough, and the card was just slightly different so as to be worthwhile. Much the same thing can be said about Terminal Moraine vs. Glaciers.
First, Moraine taps for a mana - something Glaciers did not do. Secondly, Moraine comes into play untapped, so that it can be used as soon as possible and is not as susceptible to Tsabo's Web (Web crushes Glaciers in this sense). Third, and perhaps most importantly, Moraine is playable RIGHT NOW. It's even an uncommon. No one would say that Moraine is superior to Glaciers, but it is pretty darn good.
What kind of deck can use Moraine? Well, almost any deck that uses the super-slow Lairs could be upgraded with 4 Moraines. I have an IBC Zombie deck that is heavily metagamed against green and needs three colors. The Lairs were okay, but swapping them for Moraines was a huge difference. Tight, three-color decks that have lots of land but need lots of different colored mana need Moraines.
Second, I have seen a couple of potentially terrifying pure (i.e., non-splashed) five-color decks and Moraine is just the shot in the arm these decks need to become ever more tournament viable. One of these decks used Untamed Wilds, Rampant Growth, and Harrow. Clearly, Moraine fits in this deck. In fact it is openly comparable to Untamed Wilds and is better in that it is free, can be used as an instant, and taps for mana.
Just as Quicksand, Stalking Stones, and Reflecting Pools were good, but not broken lands, Terminal Moraine is the unsung (as of now) hero of Planeshift. It is reasonably priced and easy to use. It gives you basic land of any color and, in a pinch, boring old colorless mana. So stock up on the Moraines for IBC and T2. To quote Frank Herbert: "The sleeper has awakened!"