re: Poker & mobile poker?
I don't think it has anything at all to do with the possibility of it being hacked because the client side program has no way of hacking into the server side program. Otherwise there would have been hundreds/thousands of hacks from the PC versions over the last 10 years.
What it likely has to do with is the fact that right now there are so many different mobile phone platforms(Android, iPhone, Java, Palm, Screen sizes, etc.) that it would be hard as hell for them to cater everyone's needs. And by catering to one usergroups needs, but not another's you are pissing some people off, whereas if you just don't have it at all, no one is expecting their needs to be catered to over another's.
Another thing, which has been stated before already, is the issue of cell phone's and their reception. The last thing they need is people timing out constantly because they are in a bad cell reception area.