Several support much wider gamuts than sRGB. It tends to get more expensive once you go to those kinds of printer hardware though.
www.drycreekphoto.com/ is a good resource
http://www.westcoastimaging.com is an example of one of these classes of printer, as is
http://www.calypsoinc.com/ http://www.hollandphoto.com in Austin also support profiled images and provide great results.
I've printed with both west coast imaging and holland and they were very helpful over the phone, in terms of profile setup and other pre-flight issues.