Light Bulb Cost Comparison (Incandescent vs. CFL vs. LED)

As many people are know or soon will learn, the Energy Independence and Security Act (EISA) of 2007 created a new federal performance standard for electrical lighting.  While not strictly a ban on incandescent bulbs, it will effectively act as one unless manufacturers are able to drastically increase the efficiency of incandescent bulbs.  The new standards will be phased in starting 1 January 2012 through 1 January 2014.
So what does this mean to us consumers?  When we go to Home Depot to pick up some light bulbs, we'll likely be faced with two primary technology choices: Compact Fluorescent Lamp (CFL) or Light-Emitting Diode (LED).  Which should we choose?
There are many cost calculators and opinions scattered across the web, and I recently came across a very well-presented description of the situation in an article by Martin LaMonica.  The answer?  It depends.  LEDs generally have a higher retail price, a much longer lifetime, and consume less energy than CFLs.  If the bulb will be used a lot (at least several hours per day) then it may make financial sense to get an LED.  If you're only using the bulb a few minutes per day (e.g. in a closet), then it probably won't make financial sense to get an LED.  Generalized analysis like this is provided in many places, but I wanted more detail.  In order to provide a more detailed cost comparison of the relevant variables, I put together this simple spreadsheet that allows one to input values according to their specific situation and see the expected cost comparison.
In the spreadsheet, one thing you'll notice right away is that both CFLs and LEDs provide relatively large savings over incandescent bulbs.  The trusty ol' incandescent bulbs look so inviting on the hardware store shelf because of their low price, but they'll more than make up for that in energy costs.  The CFLs and LEDs cost more up-front, but their energy-sipping ways will definitely save you money over time.  CFLs have come down drastically in price in the last several years, so much so that they will likely create slightly larger savings for the average customer than the LEDs.  The LEDs are more efficient than CFLs, but the retail prices are still quite high (though they are expected to soon decrease due to wider usage and thus larger manufacturing volumes).  Once prices do start coming down for LEDs, they will likely surpass CFLs in cost savings.
Of course, cost savings may not be the only purchase criteria for you.  CFLs are manufactured with mercury, and LEDs are not.  People who are concerned about exposing this poisonous metal to the environment would likely want to spring for the LEDs.  Likewise, the conservation-minded who are just itching to have the most efficient technology will also likely go for the LED.  One side note - I've heard some people mention that they buy incandescents over CFLs because of the mercury issue.  However, if you consider the extra pollution emitted from a coal power plant used to power that incandescent bulb, the CFL actually introduces less mercury into the environment (here is a link to the audio transcript that further explains this).