According to the press release, the site's founders (Simon Fisher and Christopher Taylor) "believe Ocula will stimulate the Australasian market by allowing art enthusiasts to research, buy and sell art around the clock and from any location."
As far as I can figure out, the site is made up of several parts. There's a Galleries section, where invited galleries have profiles that how current exhibitions, listing of their artists, and works by these artists that are in stock.

Clicking around this section however, I didn't find any prices, just instructions to contact the gallery for a price. It's always bemused me that dealer galleries put price lists on their walls but so rarely do so on their websites.
Then there's the Auction section. For a minute I got excited and thought maybe works from dealer galleries were going to be offered for auction, but reading further into the site, it seems to be the traditional model of owners consigning works to Ocula, who show some of these works in their Auckland showroom, but run all the auctions online.

I have to say, when you're on the site this is a little unclear. This work by Shane Cotton that's for sale, for example - is that being offered by one of his dealers, by the artist himself, by the owner (using the site like TradeMe) or by Ocula? I daresay it's all in the fine print (and yes, I am outing myself as too lazy - or frustrated - to open all the headings on the subpages so I can skim for the info I want) but it's not immediately apparent - certainly not with the clarity with which existing auction houses present their catalogues online.

One feature I do really like (squished thumbnails aside) is that Ocula is sucking in sales info from the Australian Art Sales Digest, which shows you how much works by an artist have made in recent sales. As far as I'm aware this information was subscription-based recently, and it's data gold.
The site is also curating art-related articles from around the web - a useful service in itself.

It seems appropriate that the first work I spotted up for sale is by Billy Apple. Bidding appears to be Trade Me style - a suggested opening bid, an auto-bid feature, and a tracking feature. Will people display Trade Me-like ferocity and bidding techniques? Not to mention Trade Me-like loyalty? Only time will tell.
[One final note. It's still not clear to me why auction houses seem to be able to skip copyright clearance on the artworks they publish in their catalogues. Does anyone have an answer on this?}