In San Francisco, it's literally hard to drive down a city block and not see a sign for a yoga studio. Bikram, Ashtanga, power yoga - they're all available and not just in yoga studios. Yoga has infiltrated the gym as well; at the YMCA where I work out, at least one if not three yoga classes are offered daily. If you're thinking about taking up yoga, it has a lot going for it. Not only can it increase your strength and flexibility, yoga can also reduce stress and maybe even lower your blood pressure.
Just remember to start slowly, especially if you have any kind of injury. And it's good to start with a small class, where you can see the instructor and get individual attention; most of yoga is about holding very specific poses and postures, and you'll probably need help at first. Once you know the poses you can move on to power yoga or yoga flow, both of which will keep you moving and burning more calories. If you try Bikram, remember, they keep those studios really hot, over 90 degrees Fahrenheit, so you'll sweat a lot and may be dizzy if you move too quickly from a downward posture to standing up.
One last thing: try not to compare yourself to others in the room. Some people are naturally "bendy" and others may not be able to touch their toes, but one's flexibility has nothing to do with how successful they are at yoga or how much enjoyment they get from taking class.