I never paid attention to it until I read about it on some site. Then I finally noticed it as a neat little extra to the show. I even decoded a few things on my own. The direct character substitution makes it pretty easy and David Cohen (on commentary) said webmasters figure it out pretty quickly.
The site also showed an AL2 screen grab (from Byclops) and they had no idea what that was all about. Naturally, without more help it would be too hard to figure out. I looked it up this year and saw how it works. The whole mathematical thing about AL2 is one thing I thought was pretty slick. I wish they had the "B" character so the font would be complete. My signature also has a message in AL2.