According to the Lindens there is coming an age verification to us in about one week. If I read the FAQ correct, it is done by a third party company and you've got to provide them some info, e.g. social security number, drivers license number, passport number, to verify that you are over 18 years old. If you provide the info successfully, then you've got the "age verified" flag and are allowed to enter parcels with "adult content" flag. If you don't have an age verification, you still can play in Second Life, but don't enter such regions anymore.
The question I asked myself can be split up in two parts: how is this going to influence the game and is this verification process going to be really secure?
Well, the first part is: I expect, who until now enjoyed adult content, are going to leave the game, since they are not willingly going to provide the necessary infos. I can understand them. If you take a closer look at the search and don't check "mature content" in it and search for some things, like escort, you're still going to find such content. Now the Lindens want that the people rate themself or they are going to take measures against them. If you take the big size of SL into account, it is not hard to predict that many people are not going to rate themself properly and that, if any, actions are going to be taken against them, this would take quite some time and they would still try after that, again.
Second: is the process going to be really secure, meaning, can I be really sure that the avatar if flagged "age verified" is played by an adult? After reading the FAQ: plain and simple no! It is no problem at all for most teenagers to lookup such infos, like a social security number, in the documents of their parents and pretending to be their father or mother. To be really sure that you are who you pretend to be you need a personal review of a trusted 3rd party in real life.
And even, if you would be checked up that way, there would be no security in it, since the son of the father just could have looked up his password with e.g. a keylogger.
So in short: while the idea of it seems nice, you are not going to have real security at all with such a kind of a system. In reality it is not going to be introduced to make SL a safer place for all, but to protect Lindenlabs better against possible lawsuits, which in result still benefits the community, though, since all of SL well being depends on LL. Period.