I have received questions about what is meant by a "poster-style" paper.
ANSWER: I am specifically referring to the one page submissions in the GP-97 conference proceedings that accompanied submissions accepted for poster presentation. The authors both wrote up their work in one page and they designed a large (approximately 4'X6' board) poster on their work. For the GECCO student workshop you are asked to submit a ONE PAGE PAPER that is similar to them. Consult the GP-97 proceeding (editors: Koza, Deb, Dorigo, Fogel, Garzon, Iba, Riolo, Publisher: Morgan Kaufmann) for examples.
This format is also the same as that of GP-98 submissions except that you must limit yourself to one page.
If you are a latex user, the style file for the GP-98 papers is available here. If you are a Microsoft-word or other WYSIWYG editor user, you should be able to make a reasonably similiar-styled page on your own.
Or, you can submit an html file.
Some students are not as sophisticated in formatting tools. It is completely acceptable to submit an ascii file approximately one page in length that is easy to read.
All of the above are acceptable.