This is one sticky subject - Lynn Tyson and Rob Williams, colleagues of mine at Dell have done an amazing job of blazing new frontiers in this area. This post has an interesting POV on blogging and IR, along with a comment from Rob...
"I agree that one of the important implications of IR blogs is democratizing publicly available information and making IR more accessible for ALL investors. And, while there are some constraints around “corporate positions” www.dell.com/dellshares is working to build our voice and bring an investor perspective and point of view to various aspects of the business. Over time, I believe dellshares will develop a strong individual voice that is based on listening to investors and engaging with them, making us a little more human, a lot more accessible and little less bureaucratic."