Oy! Your description of multi-modal communication reminds of the earlier days of Yahoo Audio Chat in the Yahoo Messenger. Often, only one of the parties could talk, and the other had to resort of typing. That was fun!

What could be somewhat realistically multi-modal is the Yahoo! Shopping or photo sharing in the newer versions.

Have to agree, it's a bit perplexing. Shouldn't they be trying to do multimodal stuff that the telcos can't copy? Why compete with the incumbents when you can be a market of 1?

It might be difficult for telcos, but it is in the relm of possibility. After all, they had ADSI phones long time back. But the difficulty is in engaging the incumbents in what is possible.