The new navbar, with its Follow and Share links, has been out for just over a week. People are starting to use the Follow button, instead of the Followers gadget - which is not necessarily present on every blog. But there are differences between the "Follow" button on the navbar, and the "Followers" gadget that's (sometimes) added to the blogs. These differences are causing some confusion.
The Followers gadget lets you login to Following, under any account, Blogger or not - and separate from the account used to login to the navbar. If you so desire, you can Follow any blog without logging in - You'll add a temporary "shadow" icon to the blog (if you choose to Follow publicly), and you'll add the blog feed to your Reading List and / or Google Reader subscription list.
With the Follow link on the navbar, if you're not logged in (using the "Sign In" link), you'll not see a "Follow" link. Once you do login (which you can only do using a Blogger account), you can click on the Follow button. There, you'll get a choice of Following publicly, using your Blogger / Google account - or Following anonymously. If you Follow publicly, you'll use your Blogger profile, as connected with the account used to Sign In to the navbar.