The code to make an LJ username link, such as vakkotaur has been modified. It's now possible to make the link say something else. If one uses the same method as before, no problem.
It has been, and still is:
But you can also do it like this:
<lj user="vakkotaur" title="Valentine Payne">
and now the link is my journal, but it will read Valentine Payne rather than vakkotaur.
If one uses the new method responsibly, no real problem - it's just a way to say a different name:
I saw vakkotaur at Siouxland.
I saw Valentine Payne at Siouxland.
But one could be irresponsible and do something like this:
I saw vakkotaur at MFF.
..and cause confusion as that link says vakkotaur but really goes to kinkyturtle's journal.
And of course there is outright trolling or namecalling possible. Just substitute something derogatory in the title section.
Of course this sort of thing has been possible all along. It's just a whole lot easier now.
I suppose there is one benefit of this. You can finally capitalize the username!