> I'm not sure how those freshly minted coins get to MtGox in the first place (any such transfer would presumably be delayed). Assuming they do have freshly minted coins in their pools, That would be consistent of some short term delays. I have experienced delays that fit this model where a Hash for the transaction has been provided but the transfer does not arrive at the other end for a few hours. Anything affected by this mechanism shouldn't be delayed beyond 17ish hours.
Both p2pool and eligius.st allow coinbase payouts to any address, and for arbitrary amounts. It's entirely possible for a person to set their mining address to their deposit one, and suddenly Mt Gox has unspendable coinbase transactions in their wallet pool. People frequently assume as you did that no spends would occur of coinbase transactions, and suddenly end up with broken systems because of it.
Here's one from p2pool, paying to 402 outputs (truncated for brevity).
Both p2pool and eligius.st allow coinbase payouts to any address, and for arbitrary amounts. It's entirely possible for a person to set their mining address to their deposit one, and suddenly Mt Gox has unspendable coinbase transactions in their wallet pool. People frequently assume as you did that no spends would occur of coinbase transactions, and suddenly end up with broken systems because of it.
Here's one from p2pool, paying to 402 outputs (truncated for brevity).
http://blockexplorer.com/tx/81e5874360f5c511ae9ad305b9797853...