Last week, SpaceX Falcon 9 rocket carried a "KickSat" into orbit. This is a CubeSat that contains about 100 cracker-sized satellites called "sprites" developed by Zac Manchester and his team at Cornell University. More than 300 people sponsored the KickSat project and will be allowed to transmit messages from these micro satellites.
The units were scheduled to be launched from their CubeSat mothership on May 4 to become the smallest free-flying spacecraft. The sprites will transmit packets every 30 seconds when they are powered up, and every 250 seconds when they’re in the charging mode. All sprites transmit on the same frequency--437.240 MHz.
Complete information on the sprites is available on Github in the zacinaction/kicksat repository.
Those interested should be able to receive signals using a Yagi antenna and one of the RTL-SDR USB receivers that I described in Software-Defined Radios Help Explore RF Spectrum in July 2012 or with a FunCube dongle.
A computer running Gnuradio is required to decode the signals. The kicksat-groundstation repository has a Gnuradio block and files that allow an SDR to be constructed using Gnuradio-Companion. A link budget spreadsheet shows a 10 dB gain antenna should work.