Seems like the upshot is that there is currently NO way to change fonts or type size in the post editor.
You're right. We cannot just click buttons like we do on Blogger blogs here at wordpress.com.
Isn't WordPress going to offer it?
I have yet to hear any Staff member state that the situation will be changing any time soon, if at all.
At present there are three methods we can use to change fonts.
1. Changing fonts in worpress.com blogs - Post by post and page by page
We can switch to the HTML editor and code in what we want. See eher > http://en.support.wordpress.com/editors/font-size-color/
2. Changing fonts in worpress.com blogs - Throughout the entire blog with TypeKit Fonts
If we want to change fonts throughout the blog then we can user Typekit Fonts
3. Changing fonts in worpress.com blogs - Throughout the entire blog with the custom CSS upgrade
we can use or we can purchase an annually renewable custom CSS editing upgrade. http://en.support.wordpress.com/custom-css/