This is a good question because I think a lot of people get confused about this. You cannot physically host a standalone WordPress
.org blog on SBI!'s servers. Now, they do have a "blogging feature" that is built into the software but it's not like the blogging platforms that we've come to know. It's more like a site index or page that automatically lists your latest content updates.
Now you can use WordPress
.com with SBI!. The difference is the content is hosted on WordPress' servers and you cannot use AdSense (no javascript allowed on WordPress.com). And you can use SBI!'s InfinIt! feature to make it look as if it's sitting on your domain.
Bottom line, if you want a self-hosted WordPress.org blog with all the bells and whistles (AdSense ads and total functionality) like my blog
http://blog.2createawebsite.com , I would not use SBI. But if you are OK with using WordPress.com (which is limiting) then you can use that with an SBI! site via their InfinIt! feature.