Change Assist provides the ability to automatically download AND deploy ESU's (Electronic Software Updates - ie the JDE Patches to functional code). Change Assistant has been available since at least Xe days (2001) - but has been improved somewhat in the past few versions of EnterpriseOne.
Because a company wants to usually start with a good, patched implementation - after an initial install, its considered good practice to go "fix current" - ie install all ESU's since the release, to ensure that all JDE patches have been deployed. I just fix-currented a 9.1 implementation (9.1 has been out since April) - and there were 1,000 ESU's I just deployed.
To go through so many ESU's - its really only reasonable to do this through the Change Assistant. Don't forget to then also go through the special instructions for every ESU afterwards....