Maybe a Coinbase engineer can anonymously tell us what's going on over there, because nobody trying to trade with Coinbase can get a public answer.
Money is going missing. Transactions have been delayed for days and, in some cases, over a week. Even amounts already in BTC aren't leaving the system.
Coinbase claimed the other day this was all due to a database migration[1], but they're offline once again.
[1]: http://support.coinbase.com/customer/portal/articles/1051063-pending-transactions