By adhering to mobile design guidelines you are guaranteed to make a BB friendly website. That's not to say that you can't go through and make an excellent website using html & javascript that won't work but there are some scripting features that the BB (and a lot of mobile browsers) simply don't support.
A good way to ensure that your webservice is going to work is to make sure that a lot of the more complex services are reliant on the back end server and provided in plain html rather than making the browser render those items.
Here's what I consider a cool example that actually does both. Helipad is a web based notepad. It'll store up to 1MB of notes and has a standard HTML interface and mobile interface.
Login to Helipad <- standard
Helipad Mobile <- mobile
Both work on my BB even though I use the mobile just for speed and the cleaner interface.
Here's a couple article from W3 that will help out as well.
W3C mobileOK Basic Test 1.0
W3C mobileOK Basic Tests 1.0
Mobile Web Best Practices 1.0
Mobile Web Best Practices 1.0