If there are others out there who, like me, prefer to start up AutoCAD® Architecture 2008 the same way they have started earlier versions of Autodesk® Architectural Desktop, with the Startup dialog, you may be surprised to find that the Systems tab of the Options dialog no longer offers the option to activate the Startup dialog. This setting was formerly available in the General Options area in the upper right corner of the tab, as seen below in a screen capture from the 2007 release.
As seen below, the 2008 version no longer offers this as a setting.
Thanks to a tip posted by ScottE in answer to his own question in a thread in the AutoCAD Architecture 2008 Discussion Group, I can report that while the ability to set turn on the Startup dialog is no longer in the Options dialog, you can still turn it on, using the STARTUP System Variable. Set STARTUP to 1 to activate the Startup dialog.
If your only use of this is to select a starting template, then you may not need to activate it. I find it useful for those occasions where I want to start a file from scratch, such as when I am creating the initial working file from which I will create AEC Content, and I want to keep the overhead in the AEC Content file as low as possible.