In the Settings, you can now choose to open links directly in Safari, Google Chrome, or 1Password. There are two ways to do this: you can choose to keep opening links in Tweetbot's own web view and then forward them to your browser of choice; or you can skip Tweetbot's web view altogether and go directly to a different browser upon tapping a link.
Opening links in Safari and 1Password doesn't have anything special to it aside from the fact that you'll be taken out of Tweetbot and into another browser. The 1Password integration is particularly useful as it is, essentially, the same idea behind my bookmarklet, only available inside Tweetbot: if you see a link for a website that you also want to log into, you can use 1Password's built-in browser to access it.
Using Chrome alongside Tweetbot is my new favorite option, as it leverages Chrome's support for x-callback-url to enable a completely automated workflow to open Chrome and go back to Tweetbot. If you open a link in Google Chrome, a new tab will open showing a back button labeled "Tweetbot"; once you're done reading, you can hit that button to automatically close the tab and be taken back to your position in the Tweetbot timeline. Chrome is smart in hiding the back button if you navigate to other pages from the Tweetbot-created tab; the browser also remembers the "special" tab if you switch to other tabs and then go back to the one created by Tweetbot. There's a minor bug in this version that will redirect to the Tweetbot's Timeline when you open a link from Mentions, but Tapbots is aware of it. For me, this is a very welcome addition to Tweetbot as it allows my two most-used iOS apps to better communicate with each other without requiring me to manually move between apps. I can get all the benefits of using an external browser (Facebook sharing, using bookmarklets) while still being able to go back to Tweetbot seamlessly.
For Flickr and Vine users, Tweetbot 2.7 also adds inline previews. Vine's short videos are shown with a standard iOS video player that has a play/pause button.