A lot of blackberry users are wondering how much faster is 3G vs. EDGE vs. WiFi. Try running this little test, it really doesn't matter what you enter into the fields, they are simply used for CNET to try to direct you to an internet service provider in your area.
Anyways, here are my results on my 8900
3770.0 kbps WiFi
2531.0 kbps EDGE
By the way, I tried running this on the Blackberry browser but it's painfully slow rendering the page, so it doesn't necessarily reflect the connection speed. Additionally, as there are variations between each connection, I recommend you run three tests per connection, and report the average for each connection modality.
I would NOT recommend using the BB for a speed test in any other way other than rendering. The BB servers compress the page and will throw off the results.
I agree about NOT performing the test with the BB browser, but when you use Opera Mini, all the pages are actually compressed on their own (Opera) servers, so that all that you are measuring is the transmission rate.