I am running 0.48.3.1 r9886 on Debian 7, and snapping when moving objects to guidelines works for me using default settings, and snapping to other objects works by changing a couple settings in the snap toolbar. However, for organizing large numbers of similar objects in a predictable way, I recommend Align and Distribute (Control <or Command> - Shift - A or bottom of the Object menu) and Rows and Columns (bottom of the Object menu); it will get you what you want in most cases within seconds.