updates
There are two pieces of software in Huawei's USB modems, that can be updated:

• the firmware, which is the vital internal operating system of your USB modem
• the content of the NAND-flashmemory, which is basicly an integrated read-only flashdrive, that contains installation files and drivers for your computer

Whereas the first-mentioned is absolutely vital, the later just spares an additional disk with the corresponding software for installation on your computer.

Usually when running an update for your USB modem both, firmware and those installation files in the flashmemory, will be updated.

Since Mobile Partner (= Huawei's dashboard software) and all the drivers are generic (which means they are compatible with any other model from Huawei and vice-versa), you can not only update your USB modem with updates designed for your certain device, but you can also use updates for any other Huawei USB modem. In that case only the flashmemory will be updated (but not the firmware, since it is not generic but hardware-specific).

Updating USB modems with updates designed for other models makes sense because updates for some sticks are quite outdated and you might want to get a newer version of Mobile Partner into your modem's flashmemory.

So owners of the E169, for which the last update was released in June 2008, can update their flashmemory with the update for the E160G from May 2009, which will bring a newer verison of Mobile Partner, while not affecting the firmware.
Also for some devices there is no update available at all (e.g. K3715). Owners of such can just use the latest update for any other device without worrying.