tl;dr: Another iPhone mount that doesn't fit my needs exactly, but works well and sells for a good price.
I was given a sample iShot 2-in-1 Tripod/Window Mount for the iPhone 4 from Abesco & Co. Design, LLC, a month or so ago, and asked to try it out, then post a review. So, here goes:
I've already used my own homemade iPhone 4 tripod mount (which was a spartan attempt at making something to hold my iPhone while attached to a tripod, but ultimately stayed in my bag. I also tried and tested a cheap and generic eBay smartphone tripod holder; it was okay, but a little finicky and unstable.
A Secure Mount...
The iShot is a pretty good in terms of how securely it holds the iPhone 4. This model is specifically sculpted for the iPhone 4, so my iPhone snaps in and out easily, and the camera hole lines up perfectly with the iPhone 4's camera. The same company also makes molded mounts for the iPhone 3G/3Gs and many other smartphones.
The iShot is also pretty secure on the tripod – the entire top half screws off the suction mount base and screws into any standard tripod head. In my testing, I used a Manfrotto ball-head on a sturdy set of Bogen legs, and the tripod mount was extremely secure—enough that I didn't worry in the least about how I positioned the iPhone on the tripod (tilted forward, backward, sideways, etc.).
...That Feels a bit Plasticky
All is not roses, though: Everything's plastic except the screws, and this means there's a loud plasticky ratchet sound when you adjust the positioning of the actual mount (see the picture to see what I mean), and I wonder how long the little plastic gears will last. That said, in my preliminary testing, everything locks down securely after you tighten the knobs.
You can position the mount vertically or horizontally, though it sometimes takes a bit of finagling. Also, the camera view, when mounting the iPhone horizontally (as is shown in this picture) is slightly cut off on the right side by the mount itself, due to the fact that the mounting arm extends so far. But you can work around this problem by moving around the mount, and adjusting all the arms on the tripod again.
Window Mount
I've only tried the included window mount once, and, while it won't win any awards for being the most solid/secure window mount I've ever tested, it is secure enough to trust it for a normal drive or a simple shot where you suction it onto a non-pourous surface.
I wouldn't leave my iPhone in it too long, though—after a few hours with the mount on my counter, it simply popped off. Buyer beware :-)
A Good Value
Overall, I rate this mount as a good value, and a great option among many. It was shipped quickly, and it only costs about $18 after shipping and handling. It comes with a little instruction manual, and it is still standing after about four different uses on two different tripods.
Buy it online at http://www.iphone2in1tripodmount.com/buy-now---phones--gps.html for about $20