Gareth Heyes has a new post that shares some of his efforts to write "non-alpha PHP", using characters other than the alpha-numeric ones to write executable PHP scripts. In his case, this involves a lot of pluses, underscores and square brackets.
I started to try and break the 10 charset limit of PHP non-alpha after @InsertScript showed me that PHP Dev supports  syntax for arrays. I wondered if it would be possible to break the limit within production PHP. At first I thought you could but then after some testing I found that there was no way to concat without "." and no way to call a string as a function without $ and =. However since I got into PHP Non-alpha again I thought why not try and improve it and make the code tweetable.
He works through the whole process of his discovery - starting with the creation of a non-alpha version of "0" (zero), moving into letter creation and finally all the way up to a full word..."assert". The result is tweetable code that echoes that string and contains more symbols than letters. If you're interested in more of this non-alpha kind of coding, check out some of the other posts on his blog.