Here's a couple I did just for fun. Wanted to test some materials, especial SSS. Crits welcome

nice sofar,
but i would change some things:
the reflection of the greyish parts are to smooth and it needs more contrast. the glasparts are to glossi i think, reflection should be more defined. this would also increase the contrast between the differently shaded objects. i also miss more direct lights that would define the shapes more.

Thanks! I'll play with it a bit more when I get a chance. Gotta do some real work now

Actionart, what did you use as ground? Because it seems a bit off to me, in the first rendering the spherical object on the right has an odd black shadow on its bottom, it should be light or reflecting the red floor, should not be that black.
Did you try using the matteshadow shader? Its well suited for this production shots.

Hey Action, nice materials... I find the settup a little bit CGish (if you know what I mean).
I cant nail down exactly, but I think it might be related to:
*Sharp shadows: most product renders are done with very big area lights that result in smooth shadowing (http://www.coolstylefashion.net/wp-content/uploads/2011/10/Photography-Studio-1.jpg)
*Completaly blacked out areas: The right part of the image (including the forground object) have areas that are completally blacked out. In a studio setup photographers would be carefull to have information in all portions of the image, you can have contrast, just not that much contrast.
*Overly saturated materials: specially the ground is very saturated. It might also be related to the diffuse value being too high, as most diffuse materials in real life tend to reflect only up to 70% of the incoming light. (with exeption of some weird materials like the spectralon).

There is also this tool called lightsmith which comes with a bunch of HDRIs wich you can use to produce studio like ilumination and reflections. It will automagically place the lights in SI with some pretty useful gizmos. It will also setup light emission in a optimized way.:
http://hdrinews.blogspot.com.br/2011/03/lightsmith-lets-you-craft-your-own.html

Ps: For great product renders always work on a Linear Workflow and have GI turned on

Thanks guys. I'll give it another go later. It is a linear workflow with final gathering but I'll have to see where some of that black is coming from.

Didn't have much time but took another shot at this one for fun. I've included the studio shot reference I'm using as well. I'm not trying to replicated it exactly as there's room for improvement on it as well I think. They have a nice lens effect going on there. Anyone know of any good free tools for realistic star filters/flares etc? Mine look a bit cheap. The materials are over-saturated on purpose as an effect (the studio shot is as well). I liked the effect when I saw it.

I think I need some imperfections in the threads and other materials to reduce the CG look and also their reflections are a bit more complex. Anyway, ran out of time this weekend but will do more later...