Is there a dev aid that can simulate Windows AD on a non-domain machine, aka my dev laptop?
Yes, to a certain degree, Active Directory Lightweight Directory Services (AD LDS - formerly known as AD/AM), can do this.
It's a Windows service that you can install, start and stop on a dev machine and that works very closely like the "real" Active Directory.
There are some limitations - see the MSDN docs for details.
Marc
UPDATE: AD LDS comes with Win Server 2003 R2 and Win Server 2008, or can be downloaded under its old name AD/AM (Active Directory/Application Mode) for Windows XP and WinServer 2003 from here:
Depends what you want to do. If you just want to do LDAP queries then ADAM/ADLDS will do the trick. If you need the security-related aspects of AD, then no.
One possible solution is to run Virtual PC or VMware and on the laptop and have a virtualised workstation to use for your AD integration testing. In that case, I might consider also going for 2008 (R2?) on the laptop and using Hyper-V.