It's very cool, but it's also a shame that measuring in characters leads to the metagame of using 97 multi-byte Unicode characters that decode to 194 ASCII characters when reinterpreted. Almost everything is in the format:

    eval(unescape(escape`<<97 wide characters>>`.replace(/u../g,'')))

Can't they just have the same agreement that Ford Prefect had with Mr Prosser? "So, assuming I'm going to use this lossless compression technique to fit 194 characters into a 140 character tweet... how about you just show the 194 characters and say that I fitted into 140 characters?"

I suppose you could make the same argument about size-based competitions at demo parties; the limit is strictly 4096 bytes but everyone + their dog is using Crinkler to compress a 12-20KB executable down to that size. In fact, part of the effort is in aligning data and tweaking constants with Crinkler's algorithm in mind, to make the raw data more amenable to compression! But at least then, it's not a constant compression (turning any 194 ASCII characters into 97 Unicode characters which with embedded decoder makes exactly 140 characters)