Do Yahoo still take your sitemaps these days, are they worth submitting to them? Do I have to create one specifically for them or can I use ones I have made for Google?
Create a Yahoo sitemap doesn't hurt and may help your site so I would read the following guidelines to learn about, create and submit yours http://help.yahoo.com/l/us/yahoo/smallbusiness/store/promote/sitemap/index.html
It is still important to submit to all major search engines. Sitemaps help in faster indexing of your website(s). I always see to it to submit to Google, Yahoo!, and Bing everytime I have a new website.
i do not use to submit this kind of site map now days because every search engine has already update their algorithm for fast crawling of the site ..
You need to Submit your sitemap to Yahoo also because they are merged with Bing and they may overcome Google one day, so its better to submit your XML sitemap now itself
Having a sitemap and submitting it to search engines never hurts, all it does is tell the search engines of the pages on your sites that would not get noticed otherwise.
it's an option for future because yahoo is in increasing phase merging other search engine, so he can be on top in future or most searching engine so don't miss to submit yahoo site map.
Sitemaps are meant to give a better idea about the webpages and their sub-pages to the search engines to not to get confused in the pages of a site. Yahoo,being a search engine, too indexes these pages for better crawling of websites involving large no. of pages..!!