Gmail by default adds each and every address which you have replied during your email conversation. Though on one hand this is one of the best feature for many who forget email address and use search to find but on the darker side it makes your contact list a mess and the real problem comes when you want to sync it with Outlook and then to iPad.
Good news is that Gmail now has now added a setting which lets you turn this feature off and prevents emails getting added to your contact list. This way from now any new contacts message to whom you send an email will not be automatically added to other contacts.
There are few more improvements like Better warnings for typos in email addresses, ewer annoying error pop-ups, Easier transitions between certain actions, Keyboard shortcut guide for everyone and a fresh new Refresh button. More at the Official Gmail Blog.