For Dell, this would finally give it a high-end solution and possibly a favored position with Oracle over HP. Dell has probably been one of the beneficiaries of Sun's slide, Getting the Sun installed base would allow it to wrap these customers first with Dell service, enhanced by Sun's own services group, and its vastly stronger (than Sun) X86 portfolio. In both cases, this would strengthen Dell significantly against both IBM and HP and make it the company to displace in a market tightly focused on cost, which is a market Dell was made to play in. The tighter relationship with Oracle gives it a better bargaining tool with Microsoft and further increases its stature when bidding against HP and IBM. Finally, this could do more to change the perception of Dell as a PC company to more of an HP- and IBM-like full service company than most anything else it is likely capable of doing this decade.
For HP, this would be a massive move against IBM on three vectors. First, it would give the company enough additional market share to distance itself from IBM and become the undisputed market share leader in servers, at least initially. Oracle would feel the most comfortable with HP, and HP would be more comfortable with Oracle than it is with Microsoft. Here, the end result could be a massive push not only for HP Services, but Unbreakable Linux, and HP hardware. Done right, this would be the outcome that would hurt IBM the most and create the strongest opportunity for Oracle to actually own enterprise Linux as a platform. Both of these companies have substantial enterprise reach and executives that are in relatively close proximity and share similar backgrounds. In other words, this could become one of the biggest partnerships in the history of technology, were it to reach potential.
Wrapping Up: Bigger Than IBM
While the Sun/IBM deal was interesting and would have helped IBM software substantially, it wasn't that beneficial to IBM hardware and outside of IBM, wouldn't have had that much impact except on HP.