Two years ago the first version of GNOME Online Accounts (GOA) was released and Empathy got the ability to use the GOA accounts that supported chat. This feature was a bit incomplete as you could configure Google and Facebook accounts in the control center (through GOA), but the other accounts could only be configured directly in Empathy. Similarly, you could use, but not modify, GOA accounts in Empathy. This problem was not fixed before as it required a lot of work, even if (from a user point of view) it was just a matter of moving some UI around.
In the last month at Collabora I worked hard on fixing this issue (and it took more than 160 patches in several components) and now you can configure every type of IM account in the control center.
All of this was done without breaking compatibility. If your program uses the Telepathy API nothing will change; if your program uses the GOA API then it will also able to handle Telepathy accounts.
This was also a good chance to fix several UI issues (mainly misaligned widgets and too much/too little spacing between widgets), see what the old UI looked like.
The task is not 100% finished yet as Empathy still opens its own accounts dialog instead of the control center and there are also a few other UI improvements to make.