purple@genbox ~ $ ftp 192.168.12.143
Connected to 192.168.12.143 (192.168.12.143).
220 .::Welcome to purple's FTP server::.
Name (192.168.12.143:purple): anonymous
530 Please login with USER and PASS.
SSL not available
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> put test.tar.bz2
local: test.tar.bz2 remote: test.tar.bz2
200 PORT command successful. Consider using PASV.
553 Could not create file.
ftp> exit
221 Goodbye.

purple@genbox ~ $ ftp -p 192.168.12.143
Connected to 192.168.12.143 (192.168.12.143).
220 .::Welcome to purple's FTP server::.
Name (192.168.12.143:purple): anonymous
530 Please login with USER and PASS.
SSL not available
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> put test.tar.bz2
local: test.tar.bz2 remote: test.tar.bz2
227 Entering Passive Mode (192,168,12,143,129,238)
553 Could not create file.
ftp>

anonymous_enable=YES 
write_enable=YES 
anon_upload_enable=YES 
anon_mkdir_write_enable=YES

purple@genbox ~ $ ls -al /var/ftp/
total 4
drwxr-xr-x 2 root ftp 25 2007-05-27 11:42 .

chroot_local_user
If set to YES, local users will be (by default) placed in a chroot() jail in their home directory after login. Warning: This option has security implications, especially if the users have upload permission, or shell access. Only enable if you know what you are doing. Note that these security implications are not vsftpd specific. They apply to all FTP daemons which offer to put local users in chroot() jails.

chroot_list_enable
If activated, you may provide a list of local users who are placed in a chroot() jail in their home directory upon login. The meaning is slightly different if chroot_local_user is set to YES. In this case, the list becomes a list of users which are NOT to be placed in a chroot() jail. By default, the file containing this list is /etc/vsftpd.chroot_list, but you may override this with the chroot_list_file setting.

chown_uploads
If enabled, all anonymously uploaded files will have the ownership changed to the user specified in the setting chown_username. This is useful from an administrative, and perhaps security, standpoint.

chown_username
This is the name of the user who is given ownership of anonymously uploaded files. This option is only relevant if another option, chown_uploads, is set.

Mon May 28 15:23:01 2007 [pid 5934] CONNECT: Client "192.168.12.143"
Mon May 28 15:23:05 2007 [pid 5933] [ftp] OK LOGIN: Client "192.168.12.143", anon password "<no_password>"
Mon May 28 15:23:09 2007 [pid 5935] [ftp] FAIL UPLOAD: Client "192.168.12.143", "/test.tar.bz2", 0.00Kbyte/sec

I don't think thats possible because thats a basic security restriction in the design of the vsftpd server , that the anonymous user must not have write access to the root folder.

Step 2) Satisfy vsftpd pre-requisites
2a) vsftpd needs the user "nobody" in the default configuration. Add this
user in case it does not already exist. e.g.:

[root@localhost root]# useradd nobody
useradd: user nobody exists

2b) vsftpd needs the (empty) directory /usr/share/empty in the default
configuration. Add this directory in case it does not already exist. e.g.:

[root@localhost root]# mkdir /usr/share/empty/
mkdir: cannot create directory `/usr/share/empty': File exists

2c) For anonymous FTP, you will need the user "ftp" to exist, and have a
valid home directory (which is NOT owned or writable by the user "ftp").
The following commands could be used to set up the user "ftp" if you do not
have one:

[root@localhost root]# mkdir /var/ftp/
[root@localhost root]# useradd -d /var/ftp ftp

(the next two are useful to run even if the user "ftp" already exists).
[root@localhost root]# chown root.root /var/ftp
[root@localhost root]# chmod og-w /var/ftp

genbox purple # cat vsftpd-solution
chown root:root /var/ftp
mkdir /var/ftp/upload
chown ftp:ftp /var/ftp/upload
chmod 775 /var/ftp/upload

purple@genbox ~ $ ftp 127.0.0.1
Connected to 127.0.0.1 (127.0.0.1).
220 .::Welcome to purple's FTP server@gentoo::.
Name (127.0.0.1:purple): anonymous
530 Please login with USER and PASS.
SSL not available
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd upload
250 Directory successfully changed.
ftp> put test.tar.bz2
local: test.tar.bz2 remote: test.tar.bz2
200 PORT command successful. Consider using PASV.
150 Ok to send data.
226 File receive OK.
110 bytes sent in 4.8e-05 secs (2.2e+03 Kbytes/sec)
ftp> delete test.tar.bz2
250 Delete operation successful.
ftp>