mapToIterable.js

import { Pipe } from 'angular2/core.js';

/**
 * Map to Iteratble Pipe
 * 
 * It accepts Objects and [Maps](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)
 * 
 * Example:
 * 
 *  <div *ngFor="#keyValuePair of someObject | mapToIterable">
 *    key {{keyValuePair.key}} and value {{keyValuePair.value}}
 *  </div>
 * 
 */
@Pipe({ name: 'mapToIterable' })
export class MapToIterable {
  transform(value) {
    let result = [];
    
    if(value.entries) {
      for (var [key, value] of value.entries()) {
        result.push({ key, value });
      }
    } else {
      for(let key in value) {
        result.push({ key, value: value[key] });
      }
    }

    return result;
  }
}

Updated version for angular 2 rc4 that works in ES5:

import {Pipe, PipeTransform} from '@angular/core';

/**
 * Iterable Pipe
 *
 * It accepts Objects and [Maps](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)
 *
 * Example:
 *
 *  <div *ngFor="let keyValuePair of someObject | iterable">
 *    key {{keyValuePair.key}} and value {{keyValuePair.value}}
 *  </div>
 *
 */
@Pipe({name: 'iterable'})
export class IterablePipe implements PipeTransform {
    transform(iterable: any, args: any[]): any {
        let result = [];

        if(iterable.entries) {
            iterable.forEach((key, value) => {
                result.push({key, value});
            });
        } else {
            for(let key in iterable) {
                if(iterable.hasOwnProperty(key)) {
                    result.push({key, value: iterable[key]});
                }
            }
        }

        return result;
    }
}

The Pipe should be defined as impure with pure: false because iterables like Map doesn't change reference when using their methods. Be careful with large iterables though.