The Tomorrowland Transit Authority is now back in operation at Walt Disney World's Magic Kingdom, having been under refurbishment for several months.
The ride has been closed since April 19, primarily due to renovation of the Space Mountain rollercoaster, one of several rides through which the Transity Authority's course takes riders. It was originally due to reopen on August 25, but this was recently delayed until September 12. Space Mountain is still due to reopen on November 22.
A few minor upgrades have been made to the TTA, with colored LEDs installed around the track (see the embedded video below) and a new coat of paint for the ride's cars. Riders are unable to see the construction work on Space Mountain, with viewing areas being covered.
Themed as a "mass transit system of the future", Tomorrowland Transit Authority carries guests on a train ride through many of Tomorrowland's other attractions.
You can keep up-to-date with the latest confirmed and rumored ride "rehab" periods using Theme Park Tourist's "Rehab Watch".