Sorry, another rant about Websphere. Don't use it. If you do use it, expect your project timescales to extend by 10-20%. It's very slow, very idiosyncratic, and despite being touted as "open standards" is actually extremely proprietary.
"open standards compliant" is open to a good deal of interpretation. First of all, Websphere is Java based, so you think "no problem, our app is Java, it'll be fine". Wrong. In Websphere 4 you *have* to use the IBM JDK to communicate with a Websphere service. This is daft, and incredibly debilitating. You *have* to install a good chunk of websphere everywhere you want to run any Java that talks to your J2EE application. That's a pretty serious liability.
Also, IBM's "extensions" to things will really get in your way. Your developers, systems admins, testers, operations staff, even the tea boy will all have problems with Websphere.
J2EE applications, the development and deployment of them, and the subsequent use and administration of them can actually be relatively pain free. Websphere will increase your running costs for the full term that you have it installed. Think: 3 years of increased cost - will that actually save you anything? I suspect not. Other app servers are better (except maybe Oracle 9ias ;-).
The scary thing is that applications like Websphere and Oracle are sold by "the big boys". Supposedly they're supposed to be able to reach higher than the rest of us, and provide better stuff than the rest of us. That's quite patently not the case here. Beware the marketing, it's extremely good, and very polished. However, it will be your undoing.
Here's my Websphere ad: "In my dream, I'm running. I'm being chased by faceless people, no matter howmuch I run, I just can't seem to get away from them." Voice of shrink: "you're obsessed with the image of things, and actually can't cut it when you really need to get something done". (cut to final screen, logo etc). "Webpshere - make your competitors play to win"