Yes there are Hems!
The GT30 series comes with a handy feature to help with image retention, you get pixel orbiter and scrolling bar options and both are found in the picture menu under advanced settings.
Pixel orbiter is the main one to be aware of as it constantly shifts the image on screen on a pixel by pixel basis to help stop image retention and i've found it very helpful, for the run in period set this to 'on' rather than the default 'auto' as it will really help but don'y worry it makes no perceivable difference to picture quality as the human eye simply can't see it working.
Scrolling bar is essentially a screen wash to help wipe away any potential image retention, i have only used it once or twice but it has been an effective tool when i've needed it.
More important is that you calibrate the screen in some way when you get it as this will really help with keeping image retention at bay, even if you just do a basic THX dvd calibration you will be doing alot of good. For games though calibrate using a game that has brightness and contrast screens....Fifa comes to mind but many others have this feature and use the game mode on the tv when you do this and for playing games of course.
You will need to calibrate again after the run in period as black levels tend to change after the first 200 hours but apart from that there is little else to tell you, i did find the THX picture preset a little yellow in colour but it's good for some content oh and don't forget to calibrate every picture preset that you use.
Enjoy the tv Hems, it's fantastic!