Seattle-based InstantService, a provider of online, live chat services, has been acquired, in a deal worth $17.0M in cash, by Massachusetts-based Art Technology Group (ATG). According to ATG, the acquisition will strengthen its position in the live help market. InstantService provided live chat, email management, web site analytics, and other related serviecs for online businesses and contact centers; the firm's clients include Charter Communications, VeriSign, H&R Block, Spiegel, Intuit, McAfee, US Airways and DISH Network.