I'm having this problem also, and I don't use perforce.
I just run the following command from the Powershell command-line:
It launches Sublime Text 2 with a new file with the following path:
In other words, it appears to be treating the leading double-backslash as a single backslash.
I get the same behavior if I try to escape the backslashes using \\drake\users... or if I use forward slashes as in //drake/users/...
If I attempt to open the file using the File | Open dialog, it will open. The problem appears to be with the command-line handling.
This is a regression in 2181 from the previous release.