If you have cpufreq-applet on a panel tightly packed with other icons/applets, the frequent changing of display from "600 MHz" to "1.60 GHz" repeatedly widens and shrinkens the applet size, causing everything else to shift repeatedly. The applet simply should remain at a fixed width size of the widest displayed value.
Is this bug still around? If so, would you mind filing it upstream? If you do file it upstream, post a comment to the bug report here.
This seems to be fixed in F7.