According to Asian Economies News, the Galaxy S4 smartphone will be revealed at a Samsung Mobile Unpacked event on 22 March. The site claims the launch event will take place in the US and is expected to be the largest ever.
This matches up to many rumours suggesting a launch in March following Mobile World Congress in Barcelona with a release in April. Last year, Samsung launched the Galaxy S3 in May at its own event in central London instead of MWC amongst its rivals.
There are also a couple of suggested release dates flying around for the Galaxy S4. The first is that it will be release on 15 April, according to SamMobile. Alternatively, a leaked image (above) claiming to be the Galaxy S4 has a date on the screen of 22 April which many are pegging as the release date.
Whether any of these dates are correct is up for debate and should be taken with at least a small pinch of salt. Samsung has made no announcement on the situation so we'll have to wait and see.