I am setting up a website using joomla, wordpress, and vBulletin. I have found site map plug-ins for vBulletin and wordpress. I was wondering if it would be a bad thing to have plug in site maps for the forum and blog then a site map for the links and pages for the website? So, blog would have site map and so would forum but the forum and blog subdomains would be included on the website domain however not show all of the pages to the blog and forum. Please advise me on whether this would be good, bad, or indifferent for SEO. Thanks
The purpose of a sitemap is provide one central page with links to all other parts of your website. It's so that once a crawler finds the sitemap it has access to all the other pages and increases your chance of all pages being indexed. Ideally all pages want to point to one sitemap because then no matter which page the crawler finds first it will have access to all the others. But if this is too much of an inconvenience I wouldn't worry to much about it. Just as long as each section of your site has some backlinks the crawlers will eventually have access to all your other pages too. You can also improve your chances by linking from some of your main pages to the other parts.
I just used the Joomla sitemap module and it worked fine. I wouldn't generate separate sitemaps for subdomains, as that would be opposite of the purpose of the sitemap.