The major difference here is that in order to bring BlackBerry devices into your infrastructure you need to deploy a BES - a BlackBerry Enterprise Server.
Even if you want to leverage your WebSphere Everyplace Access server, you still need a BES in place.
WEA doesn't do mail, calendar and contacts, for example, you need the BES in place to sync those items.
Essentially, you can access Domino applications two ways on a BlackBerry - sync down to the device or user the device's browser.
The other way to access a Domino database is to sync to the device.
The combination of Domino 7 and BlackBerry MDS 4.1 make this relatively simple also, because Domino 7 now natively supports Web Services in design, and MDS Studio 4.1 can access Web Services in - literally - a drag and drop fashion.
BlackBerry has posted a bunch of samples of how to access Domino databases on their website:
In addition, there are several third party tools (like mBizTECH's mDB tool http://www.mbiztech.com
) that can ease the effort.
Hope that helps.