Maybe not Yahoo search technology
A little while ago, Microsoft bough the Norwegian search tech developer "Fast". Fast has brilliant search software, but lacks the sheer volume of operations like "Live Search", "Yahoo" or even Google.
However, if you add Fast's search software, to the combined volume of Livesearch and Yahoo, we're starting to talk about a search engine that in quality could rival Google (or atleast give it some competition). This is the ticket to getting more ad traffic, since users has a tendency to choose search engine over quality, and not provider. Since MS has the option of profiling users from their search queries, they have a market for "targeted ads". What remains to be seen, is if they do with the small, acceptable, text-only ads, or if they allow flash-ads-with-sound (such as those who have started to infect the messenger. Which is why I'm considering replacements for it).
Yahoo's main problem lately, has been that their company has had leadership that hasn't had a clear direction. They've tried (like Microsoft) to be involved in all kinds of online businesses, but unlike Microsoft they haven't had the economic stamina to "try hard enough", and that has left them "halfway into" a lot of markets, with a rather hopeless image.
Microsoft has the economic stamina to be a scary opponent in any business. Their problem, is that their rather shady business practise has left a stigma. Convicted monopolist. Convicted software thief (remember STAC, anyone?) ISO Standards bribery (ooxml, in Sweden).
These stigmas affect knowledge-workers. Quite a few of these would rather work for free (with OpenSource products), than work for money creating anything that works with Microsofts products. These stigmas affect software companies, who know that unless they are REALLY large, any dealing with Microsoft is likely to end in their takeover or destruction. These stigmas affect governments, who are now slowly making law that forces open standards in all public documents.
Yahoo and Microsoft are, as they admint themselves, two companies with a lot in common. Both are trying hard to be "Jack of all Trades". Both can rightfully be labelled as "Ace of NO trade".
Now, what bothers me about this, is peoples unwillingness to read licenses. Take a yahoo service like flickr. People upload their photos there for a public gallery. How many would notice, if Microsoft changed the terms of service so that all pictures uploaded to the "Microsoft LIVE flickr service" would automatically be granted a license to Microsoft to use AND SELL (thus: Microsoft could SELL your picture and you wouldn't see any money)? Given Microsofts track record of shrinkwrap licenses, making such a change would NOT surprise me.
So, I guess it all comes down to this: Can we trust Yahoo? Can we trust Microsoft? Can we trust MicroBoHoo? If any of these answers are "NO", then it's time to cease using their services. Permanently.