Canon does little with the PowerShot SX150 IS to entice SX130 IS owners to trade them in for the refresh. The SX130 IS is a regular recommendation for me due to its AA batteries for power, full manual to full auto shooting modes, and large comfortable design that still squeezes in a pocket. None of that changes with the SX150.
In fact, it seems to have all the same shooting modes (except for the addition of a Discreet mode that shuts off all noises and lights), the same 28mm wide-angle lens with 12x zoom, and the same 3-inch LCD. What's new is an Intelligent IS system that figures out what your shooting and adjusts the image stabilization accordingly; a one-touch movie record button; and a resolution bump from 12 to 14 megapixels.
One of my main issues with the SX130 IS was its slow shooting performance and there's nothing in this update that addresses that, so it's probably going to remain slow if not slower because of the higher resolution.
You can read more on Canon's site or just look for the SX150 IS in September for $249.99 in black and red versions. Or, if those new things don't sound necessary to you, look for a price drop on remaining SX130s, which is where I'd be headed.