Wireless Networking

well, there haven't been any new standards, if that is what you mean...the situation is improving maybe as folks learn. you gotta define a lot of stuff to get that question answered. security is trade-off between cost of having it and value of assets it protects etc etc. but not to bust yer chops.
you take simple steps installing wireless and be pretty secure. reasonalbly secure for most assets imho. you *have* to understand how it works. get some cheap wireless and set up up. then hack it.
wireless is easy to hack because you can't always secure the 'wire'. it can be easy to eavesdrop on with wireless notebook, say. so you minimize how easy that is (directional attennas, signal paths in inaccessible place etc etc., you remove the easy open 'doors' (change passwords and names from factory defaults, enable WEP, use bridge to bridge and refuse to talk to anything but other bridge ENCRYPT incase they do eavesdrop...)
as you know, if your building isn't physically secure, your wired network is just as wide open as any wireless one imho...
i don't know what the 'best' stuff is. not linksys, not dlink. cisco maybe? develop your specs then see who fits? warranty? tech support? if you have a talented local company, use them.
look for hidden costs in antenna cabling (will be lots more than you think betcha)

While security in wireless networking has improved, so has the bad guys.

Can wired and wireless co-exist. Sure, it all depends on how secure you want to be.

First, you have to realize that when wireless is implemented, it's automatically outside your facility... even if you can't pickup the signal with your laptop, there are amplifiers that will be able to boost your signal enough to grab packets. While WEP is good, hackers can force enough packets onto your network to break it. (not easy, but breakable) So, to keep your wireless secure, require the same thing on your wireless connectivity that you require for wired external connectivity.

For instance, my company allows VPN access into the internal network. Thus, we require a VPN connection when a wireless device wants to connect into the network also. For instance, I go to the Atlanta office and configure my laptop to connect to their internal wireless router, using that day's WEP code. My laptop then says that I'm on the network but I still can't access anything. The reason is that I've connected to the wireless pop which is handing out IP addresses, but it's connected to another router that won't allow anyone in without a proper VPN connection. So, this is the same as me hooking up at home on my cable modem and VPN'ing into the network.

Without this, it's far too easy for someone to pickup your signal and with a little effort be on your network browsing around just as if they were in your office.