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
There are still a few lingering issues, which we've been working hard to fix and will be looking at again today. To those affected, I'm very sorry for the wait. Funds are safe, it's just a question of opening the pipes properly to let them flow normally.