My company is a member of BB Alliance, but I'm not sure how much and which information I can give you respecting the NDA...
From
BlackBerry - ISV (Independent Software Vendor) Alliance Program - BlackBerry Partners
* Application development support with dedicated technical resources
* Access to preview and beta software
* Product support, such as special pricing on software and free smartphone(s)
* Marketing support, including marketing materials, joint branding and sales leads
* Complimentary listing in the annual BlackBerry Solutions Catalog and Partners Solutions Directory
* Online training support
* Sales support, including Research In Motion (RIM) Business Development team assistance, resource access and online demonstrations
... actually it's saying what you can expect
In addition you can ask for BIS-B support for your application - this is not a secret as it is mentioned in a presentation about the different ways of establishing a connection