For organizations that already run SharePoint, I love the idea of SharePoint Online as an Extranet solution. You can provision users in a completely separate repository than your AD, but you can also replicate in your AD users so they only have to use one account for sign-in. Everything's separate, but can be made seamless. In fact, I did a presentation to our local SharePoint user group about just that use case for SharePoint Online a few weeks ago. Plus SharePoint Online as a part of the BPOS offering is an incredibly attractive pricepoint for smaller organizations that don't currently have SharePoint and don't have the IT expertise to get it up and running right. SharePoint Online abstracts away all the admin pain and allows businesses to focus on improving their business values and processes through the tool. Microsoft Online Services (MSO) is going to be a big deal. SharePoint Online is going to be a big deal. Keep in mind this is still a v1 product really, MS is working out the kinks and trying to figure out what people want to get out of it. MS history shows that they don't really get it right until the 3rd release of a product, and I'd be willing to speculate that they'll almost be there w/ v2 since they're basing this off existing products. They have stated they want to see feature parity between MSO and their on-premise products in the Office 2010 wave, I wouldn't be surprised if anonymous usage of SharePoint Online is available at that time. I would also remind you that when it is available, it probably won't be cheap. The Internet-facing license for MOSS is pretty pricey, and I would think the model would be similar for that kind of scenario through MSO. That's just me reading the tea leaves though, take it for what its worth.

Kanwal, Here the service description of SharePoint Online Standard. This gives you more insight into the current functionality: "Microsoft® Office SharePoint® Online is a collection of Web-based tools and technologies that help you store, share, and manage digital information within your company. Built on Microsoft Office SharePoint Server 2007, this hosted service is ideal for storing project documents in a central location and sharing them with others. By using SharePoint lists, libraries, and Web Parts, project members can work more efficiently and productively. Intended for company decision-makers, this white paper describes the services and features that are included with the Standard offering of SharePoint Online. SharePoint Online Standard is a Microsoft Online Services offering for those who want rapid service adoption and a standardized administrative console." http://www.microsoft.com/downloads/details.aspx?FamilyID=1bef6a35-9785-4a0b-b227-387c0ee85a36&DisplayLang=en

Kanwal, Here the service description of SharePoint Online Standard. This gives you more insight into the current functionality: "Microsoft® Office SharePoint® Online is a collection of Web-based tools and technologies that help you store, share, and manage digital information within your company. Built on Microsoft Office SharePoint Server 2007, this hosted service is ideal for storing project documents in a central location and sharing them with others. By using SharePoint lists, libraries, and Web Parts, project members can work more efficiently and productively. Intended for company decision-makers, this white paper describes the services and features that are included with the Standard offering of SharePoint Online. SharePoint Online Standard is a Microsoft Online Services offering for those who want rapid service adoption and a standardized administrative console." http://www.microsoft.com/downloads/details.aspx?FamilyID=1bef6a35-9785-4a0b-b227-387c0ee85a36&DisplayLang=en