It is kind of confusing because the word bridge has two meanings.
1. A "LAN Bridge" with two boxes joining two cabled networks together via wireless. This is "a bridge".
2. The routers themselves can be set in "bridge mode" for clients.
Another example of using "bridge mode" without actually using them as a bridge:
Let's say you have a cable modem connection in your house - but you have a big house and want to cover the entire area with WiFi.
Configure one box to function as a "router" that connects to your cable modem. It will be using the NAT, Firewall, and DHCP server features of the MN-500.
Then you configure two additional MN-500's to extend the range of your wireless network. You run Ethernet cable to them and place them so that they cover your whole house. You would configure each of these in "bridge mode" so that clients would be inserted into the cabled network and get their DHCP address from the "router" box that sits near the cable modem. So you have three MN-500's acting as "Access Points" - but only one is acting as a "router" (DHCP server, NAT, Firewall).
Your wireless laptop could then roam between any of the three MN-500's without changing IP Address or anything else... it should work automatic. This is a great way to extend range. Also note that used this way, a MN-500 could work with other brands of equipment - as it is depending on the Ethernet cabled network.
At least this is how I did it for my friend's house over the weekend. It worked fine.
Now let's say you wanted to create "a LAN bridge". For example, say you already had a non wireless router (NAT, Firewall, DHCP server) and wanted to connect your XBox via wireless (you didn't want to use ethernet cable for your XBox).
You would get two MN-500's and create a bridge. You wuold plug one MN-500 into your existing cabled network, then plug the other one into your XBox. The "bridge" would make the XBox think it was on the same cabled network as your router and other computers.
That is what the LinkSys WET-11 can also do - but it only has 1 port - where a box like the MN-500 has multiple Ethernet ports (so you could do a printer and another computer at your "remote location"). Assume that only the MN-500 can be used with another MN-500, no "mixing" of brands in a bridge - unless you test it yourself!
I have NOT used the MN-500 like this, so not sure how you even configure it. The manual suggests it can do this, and there were discussions on Usenet that it should work this way - but I didn't find anyone who said that they had actually got it up and running.
I know that routers from Linksys (WAP11, not to be confused with WEP11) can do this.