Furthermore, for those of us who aren't quite sure how the blocks and ownership work at this level, what about the other transactions of the 289321 block? What does 289321 signify, and what about the 29,999 BTC transaction listed here?
Just that it was the 289321th block to be mined on the mainline of the blockchain.
> what about the other transactions of the 289321 block?
These are just transactions that happened within approximately 10 minutes before the block was mined (precisely, those that reached the miner between 06:22:28 and 06:34:54 today -- times in UTC I guess).
So this is a 2-year-old block, and ~$15 million (just estimating at ~500/btc) being shifted around in that set isn't abormal? (Not sure how recycling of big amounts works, I'm not being facetious)
Block is just a set of transactions. New block happens every 10 minutes and contains all the transactions that all the bitcoin users sent during that period.
So, this one transaction is interesting because it involves an old address. Other transactions in this block are probably unrelated.
http://blockr.io/block/info/289321