One thing you can now do with Lightroom in the Develop module (not the Library module) is use Soft Proofing for images that may have colors that are out of the gamut of your "target" color space (typically colors that are real bright/rich). The Soft Proof "function" allows you to softproof for your display gamut or a print "profile" but it can also be used to "proof" your "destination color space".
This can be useful if the image has rich/bright colors. If you check Lightroom's "normal" histogram, it reflects the ProPhoto color space and, assuming you correctly exposed, colors in the histogram will look "in range" since our camera sensors can capture a wide gamut of colors and the LR ProPhoto gamut can handle a wide range of colors.What is not evident is the possibility that the bright, rich, saturated colors may push beyond the sRGB gamut or the Adobe RGB gamut.
This is where Soft Proofing comes in. It has three features that can be useful. First and foremost is the histogram, which reflects your destination color space. For example, I did a three classic car show shoots this last summer, with plenty of richly colorful cars, bathing in the light of bright sunny days. Well, in Lightroom's "normal" mode the histograms show all the colors "in range". But, if I press the "S" key, turning on Soft Proofing, the histogram tells a different story, with the brightest colors jammed up against the wall! This can also be the case with colorful flowers, an colorful garments and other colorful subjects.
Another useful tool is to show Destination Gamut Warning (Shift-"S"). Do this and you will get a "visual" of what the histogram showed you -- a bright red "overlay" will cover the areas that are out of your destination gamut. Scary stuff, if you shoot colorful subjects.
The third feature is that in the Soft Proof mode the Preview is rendered using the Destination gamut. If the Preview differs from the "normal" preview, well, that's a hint of problems you might encounter in a print or Web presentation.
I should say, though, that how the Preview displays will vary from monitor to monitor. In a "consumer" monitor, your monitor gamut will not handle wide gamut colors, so you won't be really viewing an image in the ProPhoto color space in the "normal" preview, or even in image in the Adobe RGB, so it's unpredictable how much the Soft Proof preview will show you.
Then, the question is, what should we do about those colors that show "clipping"?
Well, that's a good question, but it's one that doesn't have a simple answer! For example, I've put some of those car show shots out on my Web host without a problem. But, there have been times when I've "tweaked" colors that I knew would clip. How you handle these things of course would vary on the "questionable" image and then on your judgement and preference!