In early February, the FDA approved orlistat, formerly known as prescription Xenical, for over-the-counter sale. Orlistat is a blocker of fat absorption.
The new OTC version will be called "Alli" (pronounced like "ally") and will come at a dose of 60 mg to be taken three times a day with meals. Prescription Xenical came as a 120 mg tablet. However, the company claims that the reduced dose sacrifices only 5% in reduced fat absorption, dropping from 30% with Xenical to 25% with Alli. It will cost in the neighborhood of $1 to $2 per day, or $30-60 per month, far less expensive than the $110-150 for the prescription form.
Does it work? Is it worth the money? Clinical trials document around 5-10 lbs lost over a 3 to 6 month period, 50% greater than using diet and exercise alone.
Our experience is that it works, though inconsistently. Results depend heavily on how reliant you are on fat calories. If you were to follow a low-fat diet while on the drug, you likely will lose little or no weight, since there's little fat absorption to block. However, I have witnessed more substantial weight loss of 10-20 lbs. in people who follow a higher fat intake in their diet, e.g., a traditional American diet. However, these people gain the weight back immediately because they've made no effort to modify food choices.
It is messy. Even though the clinical trials claims modest inconvenient effects like gas and greasy stools, I have found that it is, without fail, a very annoying product that results in crampiness and frequent messy stools in nearly everybody.
The company has created a glitzy website that you can view at www.myalli.com and promises to provide a personalized program and support for registrants when it is up and running by summer 2007. 
I think that's a good idea, since the drug itself is no more than a temporary fix unless it's combined with long-term diet changes. However, the website, I believe, oversells the value of the drug with a drug company's usual over-the-top hints and innuendoes without actually coming out with straight pitches of the truth.
Beware of the vitamin D-blocking effect of Orlistat. The period of time you take it may be a time to resort to some modest sun exposure (10-15 minutes; be careful not to burn), rather than than oil-based vitamin D capsules, in order to avoid the inevitable vitamin D plunge in blood level.
I am not a fan of orlistat, having seen it tried many times with minimal success. However, it is another option for those who are really struggling. Personally, I would try fasting or some of the other strategies we've detailed on the www.healthcare.gov website before I resorted to orlistat.