Here at We Love Mobile, the big question is, why? Why would we want Yahoo! to be our mobile home-screen. Aren't internet portals for lazy people who never make it past their ISP's walled garden? Does anyone persevere or spend any time on web portals like iGoogle. And more importantly, do portals like this fit in with mobile usage?
Overweight offerings like Yahoo portal don't seem to really fulfill any need apart from offering Yahoo! execs the prospect of mobile land-grabbing. But doing everything doesn't count for much unless you are doing everything really really well. Google manages this trick for quite a bit, but doesn't claim to the home for content discovery, for instance. Yahoo! doesn't look like it is offering anything new or better than what is already out there, its just lumped everything in one great big purple sandwich.
We have written a longer article about Yahoo mobile portal, you can check it on: http://www.welovemobile.co.uk/blog/?p=468
