For one and a half years, I have been keeping my eyes on the git community in hopes of making the switch away from SVN. One particular issue holding me back is the inabilit
git will work very well in a non-team environment where each developer is solely responsible for a piece of code or file, because in that case communication about locks is not needed.
If your organization requires team environment (usually to strip developers from job security), then use svn, git is not for you. Svn provides both - source control and communication between developers about locks.
What about cad files? If the files aren't locked, to be kept read-only as well, most cad programms would just open them an change arbitrary bits, seen as a new file by any vcs. So in my view, locking is an ideal means for communicating your intend to change some particalur file. As well, it prevents some Software to gain write access in the first place. This allows updates of the local files, without the need to close the software or at least all files entirely.
Just put a text file in cc with the file that you want to lock and then have the update hook reject it.
I would not expect file-locking to ever make it as a feature in git. What kind of binary files are you primarily interested in? Are you actually interested in locking the files, or just preventing conflicts caused by not being able to merge them.
I seem to remember someone talking (or even implementing) support for merging OpenOffice-documents in git.
It might be true, that reorganising a project can help avoiding locks, but:
To request, that a whole company might reorganise their workflow and replace all their tools that produce binaries, only to be able to work with git, because of the lack of locks, sounds quite inefficient.
Locks do not fit into the git philosophy (which was never made for binaries), but there are non-neglectable situations, where locks are the most efficient way to solve such a problem.
Im not suggesting to use git at my company for the same problem. We use EA for all our designs and microsoft word for documentation, we don't know in advance who may edit a particular file so exclusive locking is our only option.