I certainly approve of plans to extend the trolley to the Gallagher Transportation Center (terminal for the MBTA commuter line from Boston's North Station). When I visited Lowell in 1990 after arriving on a train, I did quite a bit of wandering around town before coming upon the trolley line. (perhaps the "wayfinding signage" has improved since then)
Also, one could question whether a system that uses replica streetcars qualifies as "railway preservation", but in recent years, Lowell has hosted a New Orleans streetcar from the 1920s on loan from Seashore Trolley Museum.

There have been a number of projects which blur the line between streetcar as transportation and streetcar as preservation...

San Francisco has the F line using PCCs, Italian "Peter Witts" and various international and historic cars... clearly transportation is the main goal, but it has provided a place to run San Francisco's collection of early Muni cars. They also have the cable cars... 19th century cars (at least a few parts) and technology, again preserved because they provide a transportation function.

Tuscon had the "Old Pueblo" trolley, which served to introduce the city to the idea of a modern LRV system. The line is currently out of service as the tracks it once used are upgraded for the new cars.

McKinney Ave in the Dallas area uses a variety of vintage cars (mostly former chicken coops with misc mechanical systems) as a true transportation system.

Tampa has built a line using one restored birney and modern replica double truck birney cars... similar cars run in Little Rock.

Memphis has a line with "old" and imported cars as well.

San Jose used to run restored cars on a downtown loop... the same group that restored those cars has its own site at Kelley Park...

San Diego has a new project with PCC cars making progress...

Collectively these projects (and at least a couple I have forgotten) have resulted in significant funds focused on finding old street car bodies and making them run again. Admittedly, in most cased the restorations are based on what ever trucks, motors and such are available, and can not be considered equivalent to "traditional" museum projects like the McKeen car at NSRM (which used a modern diesel and hydraulic drive) or the 3 or 4 bodies returned to operation at Bay Area Electric (Petaluma Car, Peninsular Car, one of the East Bay system cars) which use more historically correct trucks and motors, and were done rules that would be recognized by the Secretary of the Interior or museum community.

The other upside is that you see these "heritage" cars operating in city streets, instead of a museum campus. They preserve function i.e. moving people better than a fleet of properly restored cars in a car barn.

Randy

Randy -

One that you forgot is the operation of the PCC cars in Kenosha, Wisconsin. I believe that they have recently received another PCC car to add to their fleet.

Les