Mobile Network Latency

Does anyone know of any decent sources of information on network latency in the mobile environment?

I searched the web and found some suggesting that (at least the 2.5G networks) were not materially worse than dialup (250ms-500ms). I spoke to some people more familiar than I with developing mobile apps, and they told me to expect numbers more in the 1-2 seconds range. Our early testing suggests that the number might be closer to twice that (round-trip ping times between phone and server).

Aside from decent data on mobile network latency in general, I'm also looking for information on the key factors affecting the results. For example, does the network latency vary substantially by carrier? Lastly, are there technological advances over the horizon that will dramatically reduce mobile network latency?

I just came by this post on the KVM-INTEREST mailing list:
[quote]
Hi All,

I have been working on network enabled MIDlets for some time and have
noticed the large variations in network times between different handsets
and operators.

I have written a simple MIDlet, which tests and reports the latency of a
series of http requests. I have posted it on my wap site at
[url]http://www.admpartners.com/index.wml[/url] for free download. The results can
be viewed @ [url]http://www.admpartners.com/latencytest.jsp.[/url] The goal of this
project is to understand where network bottlenecks really are and try to
find solutions to reduce them. I am looking for as many people as
possible to test this app, so that we could have a larger selection of
phone/operator data, than I have alone!

If anyone has any feedback or comments, these would be greatly
appreciated.

Thanks--Anil
[/quote]

Hope it helps,

shmoove

[edit]
Hey, cool. The quote tags finally work. Here's hoping that edit tags work too :)
[/edit]