Samsung has announced the Galaxy Gear smartwatch recently, but besides what I think is a pretty high price point, it came with another big caveat: it can only be used with the Galaxy Note 3 right away, and soon with Galaxy S, Galaxy S3 and Galaxy Note 2, as soon as they receive the Android 4.3 upgrades.
Samsung now says that new smartphones will be able to work with it, too, as long as they have Bluetooth 4.0 LE, and if they come with Android 4.3 and above, because Google overhauled the whole Bluetooth stack for Android 4.3. Don't expect to be able to use all of the Gear's features with the other phones, though (at least for a while), because Samsung has created some proprietary features built into Touchwiz, that only Galaxy devices can take advantage of, such as the Smart Relay feature.
I don't believe any smartwatch will be very successful, even for a company like Samsung, unless it can work with an entire platform, either Android or iOS, and it could enhance its chances of success if it will be able to work with both. Apple could probably pull it off offering a smartwatch that only works with iOS, because, well they're Apple, and they have a lot of loyal fans that are willing to buy anything that comes from them, and their userbase is quite large, too.
But before we declare any of these smartwatch successful, I think we need to step back a little, and think if this whole category will ever be successful. I'm inclined to believe it will take a few more generations before someone gets it "right", and finds that "killer app" that makes everyone want one.
I'm not convinced yet that tens of millions of people will want to buy $200-$300 smartwatches with their most important killer app right now being to "receive notifications on your wrist". I think we need to see something a lot more innovative and useful, and that can't work so well on a smartphone, before people will decide they "need" to buy a smartwatch, alongside their smartphone.
I also believe we need to see much better designs on these smartwatches than what we've seen so far with the Galaxy Gear and Pebble. A typical $300 watch looks a lot better than these.