This post by Michael Tsai on his blog is worrying in several ways.
Not only is Google doing this within its Gmail apps, but this is also being done for people accessing Gmail via other email apps over IMAP.
And those wrapped links will be preserved if Gmail users forward emails to other people over IMAP.
While it might seem like Google is being helpful, it's also giving them the potential to track who visits those links, as well as when and where from. Frankly, I don't put much faith in their claims that they're only going to hold that data for a limited time, or that it would be truly anonymized. And even if Google does nothing with this data it's collecting, I could imagine that a government agency or court somewhere might try and compel them to reveal it.