Power BI continues to be a hot topic that many people have been asking me about.
As you may know, there was an announcement in July about the new Power BI in Office 365 that is coming. Here is more information about that announcement - http://www.astaticstate.com/2013/07/office-365-power-bi-announcement.html
A lot of people have been asking for more information.
First if you want to try out the Power BI Preview, please go here to sign-up for the preview - http://office.microsoft.com/en-us/excel/power-bi-FX104080667.aspx
Second I have had many people ask me for some good resources. If you want to learn more about Power BI with Power Query, Power Pivot, Power View and Power Map here are two really good links - http://technet.microsoft.com/en-us/library/dn198234.aspx and http://technet.microsoft.com/en-us/library/dn198234.aspx. If you follow the sub links of these articles you will find a ton of good information.
Third, the biggest question I still get is does the new Power BI support the ability to connect to line of business databases. This is probably one of the most exciting things being introduced because up till now because Excel Services could only work with the data contained in the spreadsheet. The answer is the new Data Management Gateway. It requires to you to install a gateway on-premise that will make a secure connection to SharePoint Online. It push data from on-premise (on demand or a schedule) to your spreadsheets stored in SharePoint Online to render the reports through the browser. You still have the ability to open the Excel client with the add-ins for Power Query, Power Pivot, Power View and Power Map.
Here is a really good reference for you to start reading and all of its associated articles - http://office.microsoft.com/en-us/office365-sharepoint-online-enterprise-help/power-bi-admin-center-help-HA104078330.aspx?CTT=5&origin=HA104078557. There are articles that cover what the Data Management Gateway is, how it is installed / configured, how to create data sources using OData and then how to connect them into Excel. There is even a really interesting article about how SSIS can be utilized as a data source for Power BI. As well is a good article on health reports and utilization of the Data Management Gateway.