Siebot is the bot operated by Siebrand.. This one bot alone did at the last count 9071569 edits and the counter for the total number of edits is at 952027924 edits. Siebot is used for many functions, it is used heavily for Commons maintenance and for interwiki linking.
The thing with statistics is that you have to be wary of what it is a number represents. One billion edits is enormous and, they are indeed all generated by our community, some do an awesome job and automate much of the drudgery.