How can I view Google My Maps on my phone (Nexus One)?
Bearing in mind I'm using CyanogenMod6 + Google Apps your mileage may vary - but I can access my My Maps as follows:


Open Google Maps (the application, not the full site)
Click menu 
Select Layers 
Select More Layers
Select My Maps and your maps should be displayed


Job done

[Edit] Looks like I'd installed the wrong Google Apps package when I flash my ROM last night, (tiny instead of medium), and the updated version has the Layers button up next to the search bar - so I don't need to open the menu (step 2) anymore.