Name one IM app (or protocol for which there are decent apps) for a large selection of handheld and PC platforms, that isn't available for the N900.

Sorry, but there are people I keep contact with that don't have a smart phone but have a PC. And when I am at my PC, I would prefer to multi-finger type on the PC keyboard than the N900 keyboard (and even less on a touch screen device).

I haven't "switched" IM protocols or apps in years. I use skype and jabber (2 private jabber servers, GTalk, Facebook). Because I choose platforms that have jabber support, or decent jabber clients.

I don't buy into vendor-specific, I want vendor neutral (which is why I think Meego is a better option than Android). This is why I wouldn't ever buy a BlackBerry (even though they are now very popular in my country).

It's like asking for Compuserve or AOL (the closed network before they connected to the Internet) support for the N900. What is the point when we have great internet (or in this case, widely supported IM protocol/app) support?