I just wanted to say thank you to all of you so far, as info keeps piling in i keep on the hunt and it seems no source has even remotely the same answer in the same time frame. i would expect variation as bitcoins are always moving from address to address, but differences of over a few million within a few days just does not seem to add up.

I know bitcoind uses the rpc, is there any way to query the bitcoind client to spit out a current number of addresses in use without using linux? Any cool blockchain querying windows applications?