How do I access an access array item by index in handlebars?

If undocumented features aren't your game, the same can be accomplished here:

Handlebars.registerHelper('index_of', function(context,ndx) {
  return context[ndx];
});

Then in a template

{{#index_of this 1}}{{/index_of}}   

I wrote the above before I got a hold of

this.[0]

I can't see one getting too far with handlebars without writing your own helpers.

Try this:

<ul id="luke_should_be_here">
{{people.1.name}}
</ul>

The following, with an additional dot before the index, works just as expected. Here, the square brackets are optional when the index is followed by another property:

{{people.[1].name}}
{{people.1.name}}

However, the square brackets are required in:

{{#with people.[1]}}
  {{name}}
{{/with}}

In the latter, using the index number without the square brackets would get one:

Error: Parse error on line ...:
...     {{#with people.1}}                
-----------------------^
Expecting 'ID', got 'INTEGER'

As an aside: the brackets are (also) used for segment-literal syntax, to refer to actual identifiers (not index numbers) that would otherwise be invalid. More details in What is a valid identifier?

(Tested with Handlebars in YUI.)

2.xx Update

You can now use the get helper for this:

(get people index)

although if you get an error about index needing to be a string, do:

(get people (concat index ""))

{{#each array}}
  {{@index}}
{{/each}}