We have an existing community calendar/events site built with KharmaCMS. It looks good, but lacks many features. We have decided that a licensed version of Helios Calendar is what we need.
Our other main site uses WP 2.8 and we are very comfortable with it. If you wanted to integrate the Helios product in a WP environment, we would be perfectly good with that, but it certainly is not necessary. A standalone product for our events website would be fine also and the Helios software may cover all of the bases.
The finished product must allow for managed LOCAL advertising in the sidebars at least.
Our site is hosted on BlueHost and meets all of the system requirements of the Helios software as we understand it.