Widgets, soft-drink formulas, new drugs: They can all be protected by patents. But did you ever think the clever tax-saving strategy your financial adviser is offering up could be patented as well? Don't dismiss the notion. Unauthorized use of a patented method might get you into hot water. John Rowe, executive chairman of health insurer Aetna, knows that all too well. Within the past three years, at the suggestion of his advisers, Rowe set up two trusts and funded them with nonqualified stock options. An independent options valuation expert estimated their value for BusinessWeek at $28.5 million. Rowe's so-called grantor retained annuity trusts [GRATs) would pay him an annual income for a specific time and reserve whatever is left for family members. Plus, he could achieve dramatic gift-tax savings, says Carlyn McCaffrey, a lawyer with Weil, Gotshal & Manges in New York who is an expert on GRATs, though not involved in the case.