Yahoo's new map service doesn't work properly with Firefox. Forget Safari. Same story with their mail beta.
Yahoo was fingered recently in a NYT spyware expose -- they funded malignant spyware installation.
Conclusion -- irregardless of whatever anyone may be saying, Yahoo's days are numbered. Look for an acquisition. Microsoft has their choice of either AOL or Yahoo and both are playing as nice as they can. My guess is that Yahoo goes to Microsoft and AOL disintegrates with Google picking up most of the pieces.