Actually for me I would not be buying them as I am using a FZ50 which I love.... :bsmilie:
But personally given a choice of only either two, I would choose the SX10IS over FZ28 mainly because the ability to expand when you grow with your system (I already own a 580EX2, which can be use with the SX10IS). ;p
PS: To me the SX10IS's flipped LCD & external flash feature is great for event shooting, however the IQ & color tone on the FZ28 better than the Canon offering... :sweatsm: