There are plans to replace the greeter in GNOME 3.2 which is due out in a couple on months. Here is what is is the login experience is planned to look like:
The GNOME sheep seem to be following Bill the Microsoft shepherd. Maybe I do not understand security but surely it would be better not to expose usernames.
In the days of yore, you had to remember both a username and a password. Nowadays the trend seems to be to expose the usernames and simply rely on the strength of a password for security. If I recall correctly, this started in Microsoft Windows 98.
I sure hope that support for the traditional login paradigm of both username and password continues to be supported but I suspect not.