Dot sourcing can be a bit confusing. I generally perform an include like this:
# HP AS password management
. lib\hp-pwd.ps1

# MS Active Directory Permissions
. lib\DSperms.ps1

with my generic functions stored in the “lib” sub-folder to the parent script.

If you prefer to use variables, Jeffrey has a pretty funky function that works really well: http://blogs.msdn.com/powershell/archive/2007/06/19/get-scriptdirectory.aspx

Just beware trying to use it from within PowerGUI as it currently doesn’t work as expected.

Cheers,
Adam