This is a highly speculative article that quotes various analysts' thought about a possible acquisition of Sun. This year Sun went through a round of lay-offs (again) as a cost cutting measure, which makes me believe this is not a completely unthinkable scenario.
A remote chance of Microsoft acquiring Sun was also discussed in the article:
This doesn't strike me as even a remote possibility. Sun's recent open sourcing of Solaris, Java and NetBeans makes it clear that Sun is more inclined toward OSS. Microsoft is a company that makes its money from selling software and not hardware. Donating money to Apache foundation is one thing, but rolling up the sleeves and getting their hands dirty in the open source arena is a whole another thing.
Even though Microsoft would like to see its Operating Systems running on Sun Servers I don't think they'd want to start selling servers anytime soon.
Sun has made some of the wonderful innovations in the filed of Operating Systems (DTrace, ZFS, OpenSolaris etc) and Computing (Java). It'll be sad to see them get bought out.