Ebox Platform is a very capable SME server web administration interface. Some work has been done already but limited resources have mostly hamstrung this effort. This tool set is currently optimized for Debian Sarge, but alpha packages do exist for Gutsy. This is a unique and effective administration tool that would give Ubuntu a leg up on other Distributions competing in the SME server market.

http://www.ebox-platform.com

Link to Packages:

http://www.ebox-platform.com/ubuntu

In the server install tasksel menu, include a "Domain Controller" option that allows for a (more or less) "drop-in replacement" for Microsoft Active Directory.

This would greatly reduce time to set up a full-fledged network in SMBs.

It would need to be easily configurable (web interface), and have functionality similar to rickyjone's Samba domain controller tutorial (see link), only automated :)

Create integrated directory service based on ldap and kerberos. Automatic way to create new domain, script to add workstation in domain.
Ubuntu reps has all packages needed for that, but don't has simple way to do such things.

But powerful design need some coding, changes in nssldap.
Also we need openldap overlay smb5kpwd, powerful instruments for editing directory.

Nssldap dont get way for cross realm.

Currently the only way to install predefined collections of server software (DNS, LAMP, Mail, Print, Samba, etc..) is during the text based server install, and through synaptic ('Edit' menu -> 'Mark Packages by Task') after the server installation is complete (and only if you installed a GUI!).
I think it would be beneficial for server admins to have an option during installations that allows them to install a basic xserver GUI with a server management console.

The GUI would be just a basic X environment (no need for all the useless apps). A server with just xserver-xorg, xfonts, and basic gnome installed uses almost negligible system resources anyway and [in my opinion] does not expose the system much to any higher degree.

The server management console would be similar to the "Manage Your Server" console currently present in Windows Server 2003/2008, where you can just tick a box next to DNS Server, Mail Server, Apache Web Server, etc..., click apply, and bingo they are installed. The 'Mark Packages by Task' option in synaptic is OK, but it is obscure and limited in terms of options and configurability. It needs to be taken farther.

Having used Windows Server 2003 and pre-release versions of 2008 in production environments, I can tell you that having a graphical management console on the desktop allows for much easier server management and places little resource burden on the system.

It would make ubuntu much less intimidating for windows server admins if there was a gui which allowed configuation of common network services such as:

web
ssh
mail
database
vpn
dhcp
ldap
dns

Some of these are easier than others but I have seen very little work on this front and I think it will help win over windows admins.

In order for ubuntu server to really compare to rhel it needs to improve it's integration and support for various SANs and fibre channel drivers. Yes, you can get it to work today, but it requires some hacks.

Initially I doesn't make sense, I know it. But, some times when you try to install the Gnome or KDE desktop after the default installation it doesn´t work very well or at all.
It supposed to be a server system for Linux experts (and it is absolutely well done), but also it should consider be able to been administrated by a new web master like me.
This make sense when you install de server system in a remote sever. It is so difficult to start the GUI without an assistance service.
(Or include the option at least)

There should be a good, web-based certificate authority that can be used to secure an organisation.

SSL CAs can be used to secure connections between machines (VPNs like IPSec etc.), to access services securely (https, email upload/download, etc.), to avoid passwords (single sign-on using pam), to log in with USB keys rather than passwords, to encrypt email, to setup chains of authority within an organisation...

SSL certificates are VERY useful... especially when integrated into a proper PKI infrastructure. We already have the core tools for this in OpenSSL. The problem is that OpenSSL's command line tools are a little more cryptic than the most cryptic commands I've ever seen.

In comparison, Microsoft's Certificate Services are quite straightforward.

There's no reason for this to be complicated just because it's a powerful tool. Why not make it easy for users?

It would be great to have Zimbra as a standard package. This would be a convenient way to setup mail server (dovecot for POP/IMAP, postfix for SMTP), antivirus, antispam, a neat web interface, mobile access etc.

Cups frontends all ask for a password for saving the printer setup. To make this work with your default user account, you'll have to add the shadow user group and add cups as user to that group.

Sudoers should be able to change printer settings using their login and a cups frontend without further steps.