There have been quite a lot of threads lately with people complaining about the size of the block chain, specifically (1) how long it takes to download for new users and (2) the amount of disk space used, often combined with complaints that the "core dev team" isn't doing anything about it.
This is just a quick note to explain where we're up to with this.
Starting from a few days ago, MultiBit is the default recommended desktop client on the bitcoin.org choose your wallet page. MultiBit is a what we call an "SPV wallet" so is capable of processing thousands of blocks per second, and its checkpoints are refreshed frequently enough that for brand new users, they will usually be synced with the chain in 5 seconds or less. I'll explain a bit more about how this works in a moment, as we have many newbies join us in recent months who may not be familiar with the details.
At some point Bitcoin-Qt will change such that it's able to delete old blocks. The details are still being worked out, but most likely you'll be able to say "Use up to 10 GB of disk space" and it will never use more than that. Nodes will broadcast how much of the chain they have and are able to serve. New nodes that are starting from scratch will have to search out other nodes that still have the full chain and sync from them, but any node that just wasn't online for a while and needs to grab the latest parts of the chain will be able to use most of the others. By controlling disk space usage, you can also indirectly control bandwidth usage (you can't upload data you don't have).
