Today Gmail rolled out yet another awesome lab (experimental) feature: Send SMS text messages via gTalk from the comfort of your Gmail client .  Testing it this morning with a friend's iPhone, the new feature works fast.  Responses sent from the phone will go back into the gmail chat window.  Interestingly, though the gmail sender's email address is shown, the actual sms sender/from field appears to be a random number.  With all the millions of gmail and gtalk users, I wonder how they assign these.

This latest labs feature is notable because it circumvents a traditional revenue stream for carriers.  Most mobile carriers still charge separately for data and SMS plans.  Since users of Android on T-Mobile have the option to use 400 txts for free or supplement data plans with unlimited texting for $10 more, why would they pay more?  This could be a major test for T-Mobile and Android's openness.  Will T-Mobile ask Google to cripple this feature?  Looking ahead, I envision further battles looping when Android or iPhone apps will force carriers to rewrite the business rules because of new applications.  For example, future apps will let users tether their phones -- meaning you can use your phone's data plan to connect your laptop to the web instead of paying extra (often $49 or more/month) for a pcmcia data card.