Just a quickie, and looks like it is not a Revit 2010 thing. Might seem like a no brainer, but is one of those things that you can spin your wheels on and waste time with.
Let’s say you’ve just aligned something in Revit (say it with me – “destination, traveller”). You want to click the handy padlock to constrain it, but… oh no! No constraint lock! What the deuce is going on?!
It’s there, don’t worry. Check out your Visibility Graphics (VG). Look under the Annotation Categories tab for “Constrants”. Make sure that is checked. POOF! There they are!
Like I said, this seems to be OK in 2010. The constraint lock will show up after you align something even if you have the Constraints category hidden. What won’t show up are any locks on already constrained objects when you select them.