I made a photo post along with a bit of text on my Google+ profile. A few minutes later I searched Google for a portion of that text. Guess what? My Google+ post showed up #2 on Google's first page — less than five minutes after I posted it. I have seen this happen before when I've posted a link to a new webpage on my Google+ account. That new webpage almost immediately (within minutes) shows up in Google search.
Yes, Social Bookmarking is one of the best method to get indexed in SE quickly and it also helps to bring traffic to your blogs.
I have noticed the same in Facebook, Wordpress, twitter and few more social media sites. That is why these site were used to share the website services and products.
Also "Google site map for video" plug in works really really well~! you just have to create a post with a youtube video on it and generate the site map through the plug in~!
Another good way of getting a page or post indexed fast is doing it manually. Go to Webmaster Tools and then the Fetch as Google, insert the link there and it will be indexed immediately
I just tested it again. I published a new web page. Then I immediately put a link to it on my Google+ page and also did a "Fetch As Google" in Webmaster Tools. As before, it was indexed and showed up in Google search within minutes!
Good to see you guys getting excited by immediate indexing. It has been practically immediate since Caffeine, and it was always like that for high PR sites. (Well, not always, but since when social media appeared). Practically any link from any page that is frequently re-cached, or any link from social media, will get a page or a site indexed quickly. That said, it still depends on your sites domain / home page PR. If the site has no PR or is not trusted, indexing can take much longer and some pages may never get indexed. In the case of your Google plus profile, things will get indexed the faster the more G+ connections you have. It's interesting, but quite predictable, that G+ are now playing a part in SEO. Find nearly exhaustive information / details on Google indexing here.
those methods are indeed fast, however the method i have named above is much much faster and will immediately index the page you tell it to. Then Google+ and links from social networks will only help it to rank higher under the specific keyword instead of helping it getting indexed.