I have a Verified/Premier Paypal account and anytime I purchase something or make a deposit, the money is taken instantly from my bank account and I don't have to wait for it
Presuming that since you are a Dwolla user that your PayPal account is linked to a bank in the U.S. What PayPal is doing is advancing to your account the money while behind the scenes it performs the ACH bank transfer. That is a service they offer because bank transactions take so long.
...so if I use Dwolla to make a deposit at Mt. Gox or CampBX with my bank account, will the money be deposited instantly like Paypal? Or will I have to wait days for the deposit?
There is probably a two to four business day wait after you enter the transaction on Dwolla to add funds.
Dwolla does have "Dwolla Instant" which is like a loan that you pay $3 a month for, and are supposed to pay it back by transferring in funds from your bank. This will give you immediate access of up to $500 (after passing their credit check application form). Dwolla Instant is not available in the State of Vermont.
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http://help.dwolla.com/customer/portal/articles/433827-instant-faq