The first thing to point out is that "no statistically significant warming" does not mean that there has been no warming, essentially it just means that there hasn't been enough warming to rule out the possibility that there has been no warming. If that sounds counter-intuitive, it is because it is, but that is the way frequentist statistical hypothesis testing works.
The way frequentist hypothesis tests work is broadly as follows: Say you have a hypothesis (H1) that you wish to support using a set of observations (X). Next you define a "null hypothesis" that is basically what you need to show to be false in order for your H1 to be true. For example, if you hypothesise that there has been some warming, then the obvious choice for H0 is that there has been no warming at all, i.e. the rate of warming is zero. You then calculate the p-value, which is the probability of observing a trend at least as large as that observed IF H0 is true. If the p-value is sufficiently small, say p < 0.05, this is taken as sufficient evidence that H0 is false so we say that "we reject the null hypothesis" or equivalently "the rate of warming is statistically significant" and otherwise "we fail to reject the null hypothesis" or "the rate of warming is not statistically significant".
Now the first point to notice here is that H0 should be the hypothesis you are arguing against. So for mainstream science, which suggests there will be warming due to the greenhouse effect, the natural H0 is that there is no warming. The "Skeptics" on the other hand hypothesise there is no warming, yet they are using that as their null hypothesis as well. This is a grave statistical error as it means that hypothesis testing no longer functions as a sanity check, as the skeptics are assuming that they are right and requiring evidence to prove them wrong. Mainstream science on the other hand are assuming that they are wrong (H0 is true) and asking if the observations refute H0 (implying, but not proving that H1 is true).
Now for the second point. If the trend is not statistically significant, there are at least two reasons: Firstly H0 actually is true, and secondly H0 is false, but there is insufficient data to demonstrate that it is wrong. Consider flipping a two-headed coin four times. The traditional test for the bias of a coin will fail to reject the null hypothesis as even getting four flips in a row will happen by chance with a fair coin more that 5% of the time. This is because the power of the test (the probability of rejecting the null hypothesis when it is actually false) is not very high.
This is the case for the "not statistically significant" observed trend we have now, given the expected size of the anthropogenic trend and the noise in the data (weather), the power of the test is so low that it is not at all surprising that the result is not statistically significant. Easterling and Wehner have demonstrated that the climate will occasionally show decadal (or more) periods with little or no trend, and that this is also found in model simulations.
To add to this, the hypothesis test assumes that you are looking at an n-year period chosen at random. If you cherry pick the start and end dates, the power is even lower, unless you compensate for the implicit multiple hypothesis testing.
The quote from the Independent does not show that it is a "data error"
A new study has found that global temperatures have not flat-lined over the past 15 years, as weather station records have been suggesting, but have in fact continued to rise as fast as previous decades, during which we have seen an unprecedented acceleration in global warming.
Saying that temperatures have not "flat-lined" is not incompatible with the rate of warming not being statistically significant, because the latter just means we cannot rule out the possibility that the underlying rate of warming is zero. The problem is that most journalists, and an even larger proportion of climate skeptic bloggers don't really understand hypothesis testing.
Saying that the rate of warming is the same as that before is not incompatible with the rate of warming being not statistically significant either for much the same reason.
The comment about acceleration needs a bit more evidence though.
The pause in warming is interesting, it is well explained as a result of the effects of ENSO (see the paper by Foster and Rahmsdorf), and it is providing an interesting area for research in climate variability. This does not however mean that the underlying rate of warming has changed, or that carbon dioxide is not a greenhouse gas etc. So the two views are not actually contradictory.
To give a direct answer to the question, whether the warming is significant or not depends on the dataset you look at, how you choose the period in question, your statistical assumptions (e.g. taking into account autocorrelation and multiple hypothesis testing due to choosing the period after looking at the data etc.). Even then, it doesn't necessarily mean much unless you also look at the statistical power of the test.