First, I didn't write this, I just found it and submitted it because I thought it was cool.

I didn't have time to check all of them to see how this differs, but I compared it to 1140grid and found that Columnar uses numerals instead of spelled-out numbers (i. e. 8 instead of eight) in class names and that it has more IE6 hacks. That's enough difference IMO to write a new one, and I'm sure I could find more material differences in a more thorough examination.

Also the market isn't saturated for fluid CSS frameworks (not even close) so if someone makes a nice website for one and can get more people to use it, I think it's a good contribution to the web!