I read this the same way as quizivex's interpretation. In addition, because you have to send the score from an entire administration, that means you can't mix and match scores from different sections of a test -- for example, you can't choose the Verbal score from Feb 2012 and the Quant. score from May 2011, or what have you. This makes sense but some of the wording on the website confused me until I realised this is probably what they meant. Also, this point doesn't apply to the PGRE of course, which only has 1 score.
But I don't know if this is necessarily a good thing or not. Firstly, I feel this will cause people to feel even more pressure to take the test more than once, knowing that they can get a higher score without showing the bad ones. This would then cause the competition to rise, which means people want/need to get even higher scores. So it's a cycle where people may not feel comfortable until they've taken the test 2 or 3 times. Meanwhile, every test taken and every ScoreSelect-ed score (to pick out the best score) means extra money for ETS and increased costs for all of us students.
Additionally, I don't think it's really helpful to be able to pick out the best score because if you submit all your scores, I think the schools will probably only consider your best one anyways. If they are vastly different, say 500 and 850, then I think the school would look at the 850 score more. If they are similar, then it wouldn't have made a difference to submit one score or another anyways.
I guess it is good though that you can write each test as if it was your first and this makes every test equal in the sense that if you scored, say 750, you don't have to worry about doing worse on the 2nd try.