Earlier this year, the 451 Group reported that the Big Four systems management vendors (BMC, CA, HP, and IBM) were ripe for a shakeup, and had been for some time. Poised at the top of a healthy, lucrative market, it hardly seems likely that these market leaders could be threatened by newcomers. Nevertheless, they are being challenged and the enterprise IT world is paying attention to the outcome. How real is the threat, and what changes will it eventually bring to the IT infrastructure management software?