This is _highly_ misleading. The actual number of nodes that they're measuring is 11,664, which is a sudden increase from a slowly declining level of about 4,400 as of a month ago.<p>The 196,123 number is a count of the number of distinct IP addresses being rumored between nodes. Most of them are never working garbage sent into the network by confused software, misguided would-be DOS attackers, etc.
I was watching this through the year, wondering if the decline was due to people moving over to web wallets. Clearly not. I bet this is a good indication of price. The more there is online, the more natural interest there is. I think over time it will start meaning less and less as people do INDEED move over to other wallets.
I think that perhaps a large portion of Bitcoin nodes are "dormant," i.e. offline until the owner feels like updating in order to make a transaction.