I'm not entirely certain, because I don't have more than 3 accounts set up, but I think this article might only apply to Blackberry Connect devices, not that I'm terribly familiar with those, so really I'm just guessing
Yes, reading the article it seems that the number of accounts that can be integrated for a Blackberry Connect device has been reduced fronm 4 to 3 from BIS 1.8 to 2.0. My understanding is that for Blasckberry devices it remains the same at 10.
I have Cingular also (which has to be the WORST implementation of BIS!), and have FIVE email accounts PLUS my blackberry.net account set up for a total of SIX Internet Email accounts, PLUS a BES account.
I have a [CMIME] service book for each Internet email account, as well as Desktop and Web Client [CMIME] service books.
Perhaps they mean a total of three PUSH accounts? The Cingular implementation has NO push accounts including Yahoo which I hear other providers have push service for.