The Marathon takes a lot out of you, and my legs were pretty sore for the afternoon following the race. Once I got going I was okay (albeit with a healthy limp), but getting started was difficult and anything that required lift (sitting down, standing up, climbing/descending stairs, etc.) was extremely unpleasant. This is pretty much par for the course from everything that I've read, so I sprayed them down with cold water when I showered (chickened out of the ice bath) and rested them as much as possible.
Yesterday, things were a bit better - the all around pain was still there, but it was less significant. My quads were still quite weak, however, so going up and down the stairs was still a big ordeal. Fortunately, I work from home so I didn't have to move around too much and continued to rest them as much as possible. By the end of the day, the overall pain was significantly reduced and the weakness in the quads was really the only major impediment left.
Waking up this morning I was pretty much in the same boat. As such, I was a bit worried that I wouldn't be able to get back to running tomorrow afternoon. I was playing with the idea of riding my bike a bit to aide in recovery, but as it was my quads that were the problem I was a bit concerned about my capacity to pull that off. I continued resting it in the morning, and things improved a bit so I decided to take the bike out and simply play it by ear.
Once I got going, the discomfort disappeared and the legs felt fine. To play it safe, I stayed within the confines of my subdivision and simply did laps of the 2 mile (~3.2km) loop. This ensured that I was close to home in case anything went wrong, avoided having to deal with high speed traffic and kept me on relatively flat ground. Naturally, I started out gradually and slowly accelerated to test the waters. Aside from a few short sprints to deal with vehicular traffic, I avoided doing anything too strenuous and kept the ride relatively gentile.
After reaching the 30K mark, I did a quick cooldown and then pulled back into my driveway. I put the bike away, changed my shoes and did a full suite of stretches to take advantage of the warm muscles. Fortunately, the effect that the ride had on getting rid of the remaining discomfort appeared to persist. The quads are still a little sore when climbing stairs or sitting/standing, but I can now walk comfortably and the limp is completely gone.
Either way, this is a significant improvement and I'm feeling a lot more confident about my ability to get back into running tomorrow evening. In the space of about an hour the condition of my legs has improved more than it did over the last two days. I used this technique after my half marathon in September and it certainly helped then, but this is a much more dramatic example of it's effectiveness.