There is a wide array of contributors to this project, what with it being open source, and it usually sees new builds published every few hours as a result.
While no official statement on discontinuing the software was made, last progress update was posted in 2007 and now seems highly unlikely that any further updates should be expected.
ZSNES has been in development since the 90's, and in that time has been fixed to run the vast majority of SNES games smoothly.
Due to it's "accuracy", it can run roms that most other emulators would break. Not because the emulation is broken, but because the roms are broken.