At first, it might appear that the ability to quote multiple posts is gone. Have no fear! Simply click the "reply" link and you will be sent to the quick-reply box with the text quoted. Scroll back up to the next post you want to quote and click the "reply" link, and that text will also be quoted - and placed where the cursor is located. There is a multi-quote add-on, which allows you to quote posts on different pages and remembers your selections. I'm going to look into that one, but the base function works better than vB, IMO. Enjoy!
This has been UPDATED with xenForo 1.3, now installed and running. There is a link at the bottom of each post "+ Quote". Clicking this adds the post as Mulit-Quote. Select all the posts you want to quote, scroll down to the quick reply window, and at the bottom you will see a button "Insert Quotes". This brings up a pop-up and lets you put the quotes in the order you want and insert them into your quick reply. It's really slick!
In addition, you can quote multiple posts from multiple forum threads! So you can surf around for an answer to someone's questions, click the "+ Quote" link to add it, then go back to the thread you are commenting in and drop it in the reply! I'm just reading up on these upgrades as I write this, can you tell?
This video explains it well. It kicks forum a-- http://xenforo.com/community/threads/editor-toolbar-spoiler-bb-code-and-multiquote.66976/