I was using Y!Go last night and I was prompted to upgrade. I follow the directions and was upgraded to a gamma release.
Here are some of the new things I found:

Address book sync from yahoo to your bb.
Automatic update interval setting.
Night time optimization.
New menu item, onesearch that searches every category.
Menu option to share Y!Go.

I don't really notice any speed improvements.

Well that is the main issue.....the speed! Geesh yahoo!!

I personally am fine with the speed. It's not a push application for immediate email. The balance of the interface is quite nice and it's easy to use in other respects.

While I do think they could improve the speed by doing a little more in the background while you are viewing other things, but the ease of use and the ability to sync my phone book, outweighs the speed for me right now. Hopefully they will speed it up for newer versions.

The only issue I've found with the phonebook sync is that when I add a contact on the web, the sync app tells me my device phonebook is full and doesn't add that contact? No idea what that's about, but adding contacts on the BB syncs to the web just fine every time.

Wirelessly posted (BlackBerry8700/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102)

We have the need for speed - so speed it up YH!!

I've been having trouble running the Y! Go 2.0 (gamma) app on my tmobile blackberry. It keeps prompting a message "Network Connectivity" saying (i assume) that it can't find an internet connection, but when i open my browser, i have no problem searching the web. what should i do? any tips?

Wirelessly posted (8700g: BlackBerry8700/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/100)

Do you have your tmo apn set? Can't remember if that was necessary with yahoo go, but try it if you haven't already.

Also, check your security permissions and make sure that it has access.

so for the dumb question, but what is this and does it get installed to the BB? Does it sync Yahoo saved folders?

Any links please?

Wirelessly posted (8700g: BlackBerry8700/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/100)

You can go to yahoo mobile page and you should see link to download OTA. I won't try to describe it--I'm not an enthusiast--but you can find several long threads here on the forum about it.

Have set apn to wap.voicestream.com and put "allow" to all catagories in security permissions. Is it because i don't have a BIS or BES on tmobile? I have a different tmobile data plan - tmobileWeb - which allows me to have unlimited internet access... but i only have a tmobile browser. (don't know if my info about my plan helps)