No. CipSoft frequently creates new items and add them to the game files (so they can be found on the market and/or Cyclopedia), but they aren't necesseraily obtainable. Some times they add an item to the client shortly before it being obtainable, but more often than not it takes a very long time or it "never" happens (until maybe some day it does).
There are many examples of items which you can see on the market and/or Cyclopedia which are not obtainable.
As for the update: usually new items are added with major updates. Sometimes they add a few items with smaller patches, for example to fix a bug. Generally, though, when new items are added to the game, they are also already obtainable, but the method to obtain it may involve extreme luck, completing a long/hard quest and other reasons that may take some time before someone actually gets it.