Been around forever. Hopefully stays that way
Ive been using Prowl since forever. Its indispensable for keeping track of two Macs — one across the room and another 250 miles away. You need Growl but thats easy to set up.
Never had any problems with downtime (that I can remember).
If you want to know what your machines are doing get this App!
Leo of BORG about
Prowl: Easy Push Notifications, v1.5.3