OOP, PHP4 & PHP5

I've been using PHP for a few years now and I'm quite familiar and comfortable with it. I'd like to start to seriously do some OOP coding and "take things to the next level". But as I understand it, PHP5 is going to make quite a few changes/improvements to PHP4's current handling of OOP. Given that the PHP5 beta has been out for approx. 1 month, do you think it makes sense to try to get into OOP with PHP4 right now when things could change in a fairly short while (not sure how long it'll be until PHP5 is released) and then have to re-learn certain aspects of OOP after getting comfortable with it? Or do you think that the change from 4 to 5 won't really be that big of a deal? I know that many people ask OOP-related questions a lot on the board, but I was just wondering what everyone thought of the jump from 4 to 5 and about trying to start learning OOP *right now*. Thanks -M