I've tried every possible combination right now. Theoretically, it can be placed anywhere within the <body>, <head> and even inside <table> or <select> elements, but if I place a simple <template></template> tag pair without anything else inside, the W3C validator (the tool I base all my HTML5 and CSS3 validation on) gives me the finger.
Can someone give me a rough example of where does the <template> tag goes in practical reality? I find no solution (or maybe the W3C validator doesn't validate the <template> tag correctly yet, don't know...).