One thing I strongly advise not to do: lie about your current salary. Why? If you get hired at the new company and it comes to light that you were dishonest about your old salary (via background check, verifying with your old employer etc), you may be in for a lot of trouble. Your new employer will most likely see this as unethical and raise questions about your professionalism in general.
What guarantee is there that the old employer would give out correct salary information for a former employee? Why does the author of the article assume that the employee is the only party that could potentially lie?
Person X leaves company Y, and her manager is not happy about the extra effort needed to fill her shoes. A month later, someone calls from company Z and asks how much X was making... Why would the disgruntled manager tell the truth?