Your ISP can engage in MITM attacks even if you're using SSL!
First, you ISP controls your access to the Internet, so it doesn't need to engage in a DNS attack, although it could. Rather, it could simply route (as in Layer 2 or Layer 3 IP routing) any and all traffic to a server in the middle (think proxy server without the proxy settings in your browser).
Next, your browser, like most browsers, is probably fairly liberal when it comes to CA root certificates. That is, it may have dozens or hundreds of root certs. A handful of these are quite trustworthy, a few dozen are mostly trustworthy and some are downright disastrous. If your ISP (or any MITM attacker) can obtain a server certificate from one of these borderline CAs (not terribly difficult), they can create what appears to be a secured SSL session with you (your browser has the fancy lock icon). However, in classic man-in-the-middle style, the SSL session terminates at the middle server. That server creates a second SSL session with the legitimate backend server. Neither end party is the wiser.
What does this mean? All traffic (usernames, passwords, bank accounts, etc.) passes through the first secure pipe, into the clear at the application level of the middle server (to be captured and later reviewed) and then back into the second secure pipe.
Whoops! MITM attack and you'd never know. Could this happen? Rogue employee at ISP. Or, perhaps a foreign country (could be a friendly foreign country) decides to snoop on your corporate email via this method.
Your best defense is to remove most of the root certificates from your computer, whether it's via the browser or some other key store or both. If you don't need it or know it, why trust it? The whole point of PKI root certificates is to only use the ones you trust.
I actually think this is more realistic than a DNS attack. Plus, the DNS attack still has to appear as a legitimate SSL session which means getting a valid SSL server certificate. However, I have no real world data for either scenario.