The "top" command in xterm gives me the following info:

Mem: 224748K used, 20800K free, 0K shrd, 1972K buff, 76036K
CPU: 4.3% usr 1.5 sys 0.0% nice 94.2% idle 0.0% io 0.0
Load average: 0.88 0.86 1.37

every 60 seconds I see the CPU value get higher, around 11/12% (usr around 9.7%)

N900 is idle with 3G connection to network (no data connection active) and Xterm window open.