I wrote the gr8signal app (in conjunction with +Tim Haak from LucidView who did all the backend work) that went live last week at the MyBroadband conference. It tracks and maps cellphone signal coverage in South Africa (although not limited to SA).
Install it and start uploading your signal coverage! (Note: map is not updated in real-time). View the coverage at the gr8signal site.
Development has moved in-house after v1.7.