The latest ETA on zZounds.com is end of June (had been end of April). I'm not saying it will be here by then--rather, it will definitely NOT be here before then.
I hate to put this in such harsh terms, but anybody who still has a TI pre-order standing at this point has got to be brain dead (forgive me, those who do, but this is tough love for your own good). Any product that's delayed over six months has obviously got some SERIOUS problems. A complete OS rewrite is not out of the question. But who's to say that this rewrite will itself be satisfactory? It may take yet another rewrite, and then 3 to 6 more months.
Unless you're loaded and can drop 2-3K USD without giving it a second thought, I would definitely wait until that machine undergoes some pretty rigorous testing by users and legitimate reviewers like Sound on Sound before committing to buy.
I've resigned myself to the fact that it will be AT LEAST a full year before I buy one a TI, if ever. Once you get used to the idea, it's not that tough to take. You just move on with your life and actually do something productive.