Allan won't like me for this (he's opposed to shortening URIs, and I've come to agree in most cases), but here's a replacement.  It's not TM that broke, but murl.  They've reconfigured the service such that the command won't work (same problem I had with tinyurl).  There's a new one called XRL that has a nice API.  This command is extremely simple but should serve your purposes.

Brett