I use a calibrated laptop (Spyder 3 Pro). It's not great, but I know its limitations.
However, I too experience colour changes between PS CS6 and a colour managed browser eg: Firefox, Chrome or Safari (all sRGB files).
In my case, my images on the web lose saturation, mainly the reds.
Also, if I browse them in windows (7) Picture Viewer, they are de-saturated, but if I double click and open them, the colour is back, same as PS. The best explanation I have come across is that ICC aware PS is using my monitor profile to build the preview, but the browser(s) are not. What I don't understand is why there is any difference when viewing sRGB files on my calibrated monitor - I would have thought my monitor profile was always 'active' for recognised sRGB files.
If I convert my images to the monitor profile in PS, but save them untagged, they come out over saturated in PS, but look fine when browsed on the web or in windows, i.e. like the original PS image.
Anyone know what is going on? Try it maybe - browse some images in windows, then double click to open them and see if there is a difference. It might just be my set up(?)