When I first heard about the WET11 back in May, I thought it might be a slightly interesting product for a niche market. But the product that ended up shipping turned out to have a much wider range of possible uses... once you understand the differences between the WET and an Access Point.
Once you do "get it", you'll find there's a lot you can do with a WET, and its superior radio performance and ability to accept better antennas are sure to win it a number of fans, too.
Update 11/13/02 - Rewrote the following summary based on feedback from my helpful readers, particularly Fritz Riep.
The main quandry potential buyers are going to face is deciding between a WET11 and its older sibling, the WAP11 Access Point. Since both are available for about $100, how do you choose? The decision may come down to your preference in product size, and for the way you want to set up your network. The main thing to remember is that the WAP11 is intended to perform its bridging tricks with other WAP11s only, where the WET11 is intended to work with other manufacturers' 802.11b devices. (A WAP11 in AP Client mode won't even connect to Linksys' own BEFW11S4 Wireless Router!) The other important difference is that the WET11 can't be set to operate as an Access Point and won't support support wireless clients that are set to operate in Infrastructure mode - the most common mode that 802.11b networks use.
And if you still don't understand the difference, go buy one of each and experiment. Hell, they're cheap enough!