At the risk of weighing into a debate that's becoming somewhat contentious, I feel I should offer a testimonial that supports Sandy's recommendation.
I have a '93 Sixty Special that I purchased in February '06, with 117,000 miles on it. I have no idea if the previous owners of this car were as meticulous about keeping a leather interior well cleaned and conditioned as I, so I went to work on the interior myself. Over the last ten months, I've tried both Lexol cleaner and conditioner on the interior leather seats, and Zaino's all in one leather cleaner/conditioner. While it certainly improved them, it left them feeling "tacky" for several days, despite going over them multiple times with dry microfiber cloth.
Sandy sent me a PM with a link to the thread on this subject, and suggested I give it a try. I did so, about a month ago. And I can say this method (dissolved Dove soap and Pledge) worked better than the Lexol and Zaino. It was also less time consumptive, and considerably less expensive.
Now, is this a long term, regular treatment? I'm certainly willing to entertain the idea that as a one-time application, it's okay, but that it shouldn't be done regularly. I'd need to hear some other testimonials on that. All I can tell you is that in the month since I tried this treatment, my Sixty Special's leather interior has never looked better, nor felt more supple. So at least at this point, I'm inclined to think Sandy may be on to something.
-Patrick