Ah, thank you! Can't believe I haven't been using the -n flag all this time. These flags don't do "exactly" the same thing as Ack, as Ack actually breaks it down by distinct sections, with newlines. It's a bit easier on the eyes.
Not if you're using SVN. Or if someone stuck a 24MB SQL data-dump with extended inserts somewhere, that has the word "unicorn" in it.
The newest version of grep has --exclude-dir, which handles .svn folders just fine.