A very nice phone that doesn't get near enough spotlight, the Samsung Galaxy S 4G (check out our hands-on) has a new Gingerbread leak floating around. The 2.3.3 build has been rooted, and it looks like the battery life got even better -- one user reports about 50 percent better battery life after updating, rooting, and removing pre-installed applications. If you're inclined, you can find all the instruction and download links at the source link.
Remember, there's always a risk involved if you jump into this sort of thing. For many, the rewards outweigh that risk. Be sure you're informed and pay attention to the instructions.