The answer of crdunst is pretty neat and the best looking answer I've found but there's no explanation on how to use and the code is bigger than needed.
The only code you need:
#element {
background-color: #cacbcf;
text-shadow: 2px 2px 4px rgba(0,0,0, 0.5);
filter: chroma(color=#cacbcf) progid:DXImageTransform.Microsoft.dropshadow(color=#60000000, offX=2, offY=2);
}
First you MUST specify a background-color - if your element should be transparent just copy the background-color of the parent or let it inherit. The color at the chroma-filter must match the background-color to fix those artifacts around the text (but here you must copy the color, you can't write inherit). Note that I haven't shortened the dropshadow-filter - it works but the shadows are then cut to the element dimensions (noticeable with big shadows; try to set the offsets to atleast 4).
TIP: If you want to use colors with transparency (alpha-channel) write in a #AARRGGBB notation, where AA stands for a hexadezimal value of the opacity - from 01 to FE, because FF and ironically also 00 means no transparency and is therefore useless.. ^^ Just go a little lower than in the rgba notation because the shadows aren't soft and the same alpha value would appear darker then. ;)
A nice snippet to convert the alpha value for IE (JavaScript, just paste into the console):
var number = 0.5; //alpha value from the rgba() notation
("0"+(Math.round(0.75 * number * 255).toString(16))).slice(-2);
ISSUES: The text/font behaves like an image after the shadow is applied; it gets pixelated and blurry after you zoom in... But that's IE's issue, not mine.
Live demo of the shadow here: http://jsfiddle.net/12khvfru/2/