Check AMSAT for the latest Amateur Satellite information.
Are you interested in working APRS through the International Space Station? Check out ariss.net
Check out KG8OC's Site for some great information on ham sats.
I have managed to make several contacts through UO-14 and AO-27. UO-14 tends to be less crowded at night (East Coast) and since it's on 24 hours a day it has many more passes to be worked in a day. More chances for that contact. AO-27 on the other hand is a real challenge. AO-27 is also known as EYESAT-1. First of all if you have ever listened to it's downlink you know that it is CROWDED, any pass. The other trick, AO-27 is only ON during sunlight or daylight hours. AO-27 is in a power save mode called the TEPR states. A good explanation or TEPR states can he found here.
The first APRS satellite, PCSAT was launched on September 30, 2001 and was put into operation to serve as an APRS digipeater. So far it is strong and sending telemtry along as digipeating APRS packets.
Click on any of the screen shots for a larger version
Below is a shot of my truck on www.findu.com. You can see my Raw Packet near the top of the screen, you can see PCSAT-1 in my digipath.
Below is shot from the PCSAT Activity Page. If you look in the list of heard stations, my truck is right near the top, KE4NYV-15.
Below is a shot from the same PCSAT page, but near the bottom where the Raw Data is, you can also see my raw packets in this list.
Below is a screenshot of WinAPRS with my truck near the bottom and the pop-up window shows my data and digipath information.
J-Track is NASA's online sat tracker.