Hi, I have an Arduino test program that successfully sends both INT and FLOAT data to Cosm.com
It's on the http://ArduinoInfo.Info WIKI here:
http://arduino-info.wikispaces.com/Cosm-Arduino
UPDATE: I have developed real-data examples with DHT11 (Temp-Humidity) and DS18B20 Temp (not done yet) and they are shown there, along with better how-to setup etc.