Are there any hosted online stores that can be set-up easily to take bitcoins?
AFAIK there are no publicly available out of the box solutions for setting up a store that uses Bitcoin. Although; there are many viable solutions using Bit-pay, their system integrates well with most platforms. If there is a platform you want to use their system for, their sales team can surely help you do that.
I have no affiliation to Bit-pay but spoke with one of their founders in length at the Bitcoin conference.
I would recommend looking into setting up a wordpress site (hosted, not wordpress.com), using ecwid shopping cart, and asking bit-pay to integrate the store into ecwid for you.
This setup is a 99% one size fits all, and you would be pioneering the way for others to follow. Bit-Pay may have an alternative solution, but I have developed several online stores (10+) for clients - and use wordpress/ecwid for both of my personal stores (after trying many others).
I created an osCommerce module that can enable you to setup a full webstore that accepts Bitcoin. It enables osCommerce to talk to your own Bitcoin daemon with orders being updated once payment is received. Then the funds can be sent on to an address off your webserver to reduce risk of storing too many bitcoins on the server. Also keeps your BTC prices updated from prices set in USD.
The module is here: https://github.com/weex/oscommerce-bitcoin