Yea, 2.3 doesn’t use post2cat.. alot of older plugins need this, which is why I manually downgraded all of my WordPress installs shortly after upgrading them. Pretty gay to get rid of something that tons of plugins rely on. Downgrade your WordPress installation and save yourself the headaches.
You could use FeedWordpress:
http://downloads.wp.xz.cn/plugin/feedwordpress.0.991.zip
read more about it here:
http://projects.radgeek.com/feedwordpress/
it basically allows you to “syndicate” posts from other blogs using their rss feed. You can just hit “update feeds” and it will grab all new posts from the feeds and put them on your blog… You can also set up cron jobs on your host to have it automatically update posts at a certain time everyday, hour, ect.