I know that when data is received through EDGE it is compressed. When using Wi-Fi connection, is the data compressed as well? I'm asking this because when I access the same website on my BB using EDGE and Wi-Fi, the data monitor shows significantly more data used when on Wi-Fi than on EDGE.

Are you getting your data through the Blackberry Infrastructure via Wi-Fi, or browsing directly to the site using the Hotspot Browsers? RIM compresses (on either the BIS or the BES) all non encrypted data going via the infrastructure.

I get data thru the blackberry infrastructure using wi-fi.

That is interesting. It implies that the RIM compression is on a portion of the link that is used only during EDGE transmission. Not surprising, but not the impression I was left with from their materials.

So I would say that you have data suggesting that the EDGE link is indeed compressed (as RIM claims) but Wi-Fi is not.

I ran two tests:
The first one was to acess BlackBerryGuy Home over wi-fi usinthe internet browser. The total data used, as reported by the e-office mobile data alerter was 93 kb. I turned wi-fi off and accesed the same site (www.blackberryforums.com) using EDGE. The e-office mobile data alerter showed usage of 27 kb.

The second one was to check my speed using the Xtreme labs speedtest. When I ran the test on EDGE the e office data counter registered 237 kb od data used to carry the test ( for the record, download on EDGE is 83 kbits/s, upload is 32 kbits/s). When i ran the same test using my wi-fi connection, the e-office data counter registered 331 KB used to carry the test.

I still dont know the accuracy of the data counter, but there is significant difference in data used to carry test number 1.

If anyone else would like to run the same tests, maybe we can get a better understanding of this.