What Crankin said - The seat on the bike is quite low, so she can easily put her feet down, stand up, whatever. No need for training wheels - her feet keep her upright. At first, she'd put one foot up behind her and push with one side, and now she's able to get a good run and tuck both feet up, coasting. I think a common brand is Strider - they had good videos on their site. This one is a Raleigh I found at REI. Just need to get a little basket and a bell on it for her now.

Thanks all. She really is as sweet as she looks.

ETA: It's definitely for outside! Knobby tires eat up the bumps in the sidewalk/path - and it's very light, so she can use it on the grass pretty easily.