The challenge this brings is ensuring the data between these two systems is managed in a way that means the activities that come back into the data warehouse can measure what comes in the operational systems. This way you always know what money you're making from your marketing activities and you can send these customer data sets back to your CRM system.
If you've implanted an enterprise resource planning (ERP) solution, you've already gone a long way to integrate your systems, unfortunately, just because you've got an ERP solution doesn't mean you don't also need a data warehouse.
If you think you need enterprise-wide business intelligence that includes that data, you need to factor in getting data feedback into that organization and into your systems, you then need somewhere to store and analyze it. You also need to consider what kind of business intelligence those solutions provider to see how you're going to progress with your business intelligence solutions if you're going to use your software as a service.
ERP solutions are package solutions, and this means that it's a 'one solution fits many' and therefore they need to be configured and tweaked to ensure they match your businesses individual needs and this can make getting the right information out of them slightly awkward, especially if you've had to bolt a management information system onto the side of your ERP solution.
You need to then decide whether you put that data in your ERP system so it then becomes your data warehouse to give you an enterprise view, or do you take your ERP data and put it in a data warehouse alongside your other pots of data and make that your enterprise view? This is something you'll need to address as part of your IT strategy.
More organizations are using software as a service to implement their core systems, this is whereby you use an online service provider to host your solution for you and access it through the web, this does mean your data is no longer inside your organization and as it's held externally, you have less access to it.
For many years business intelligence vendors were fighting with Office products like Excel, but now they're recognized as being just as integral to business intelligence as any other piece of software or solution. Everybody uses it all the time, the finance department loves it and as Microsoft gets the technology and the visualization capability within Excel improving it will probably be used even more.