CA1 positions are found in every program in the country. Most of them are filled one year in advance through ERAS. Graduates from the class of 2007 will match for a 2007 prelim year spot and a 2008 CA1 spot. That's assuming a prelim/advanced pathway. Students matching for a categorical position will only match to a single 2007 PGY1 position.
Some programs have a CA1 position or two that they fill outside the match. Applications for those positions may be through ERAS or directly to the program. If you are currently an intern and looking for a position, I'd suggest applying through ERAS and sending every program a cover letter and CV.
