has broadened its remit and turned into "Google Webmaster Tools". There's an overview of the tools available, and with the revamped Webmaster Tools Google have launched a new blog, plus new help pages, Google group and some Sitemaps enhancements.
The sitemaps feature does still work (if you're not familiar with Sitemaps see my previous posts on what's Sitemaps, plus why you'd want to "verify" your blog, and how to verify your blog/site with a meta tag if you can't upload files to your blog/site server).
While submitting a sitemap will still work in the same way (more info on how), now life should be easier for bloggers and webmasters as Google have tried to gather together in one place tools and tips to help you help Google's bot crawl and index your site - e.g. a clear link to the Add URL page to submit your content to Google (e.g. to get your website indexed by them), and to check if your site is being indexed by Google at all.
Incidentally, I tested recently whether submitting a sitemap would make it more likely that Google would index a new blog more quickly, and while Sitemaps claimed that it had been crawled, a search on Google didn't turn it up at all. So if you have a brand new blog or site and you want people to be able to find it by searching on Google, don't just submit the sitemap - I'd also submit the URL of your site. And try to get links to it, etc - all the usual! In other words, submitting a sitemap and adding the URL can't hurt, but they're not necessarily enough in themselves to get the Googlebot to spider your site and to get your site appearing high in Google's rankings.