What any cyberpunk game should include, whether 'modern' or not:
* Highly advanced personal weaponry. Things that we can imagine existing in practical use (like rail-guns) but not things that are "way out there" (like antimatter rifles).
* Cyberware. Regardless of how we envision cybernetics in the future, most of it should remain inorganic, whether metal or ceramic, while "bioware" should be very rare and extremely expensive (if available at all).
* Weak or nonexistent law enforcement at the street level. In an era of having to deal with lots of big stuff (i.e., terrorism and such), dealing with comparatively minor illegal activities will be put on a back burner.
* Psionics. Psionics goes well with technology because they are both children of the sci-fi genre, but they both have their own home turf (technology can dominate your body, but only psionics can dominate your mind). This "separate of powers" approach is handled very well in the d20 fantasy/space game Dragonstar (technology can be used by anyone, but interstellar travel is only possible with magic).
* A powerful criminal element. This goes hand-in-hand with weak law enforcement, but bears repeating (an unpoliced society where everyone is law-abiding isn't cyberpunk). Not super-corporations, but the gangsters of Chicago during the '20s, or the Klan in the South during the '60s, or the drug lords in South America today are some examples of this. Such organizations can be very dangerous and influential without necessarily having the ability to control and operate their own arcology(s) or some such.
* Secret organizations. Again, not necessarily mega-corporations or secret government agencies, but *someone* or someones who are interested in achieving the ancient dream of global domination through politics, technology, or maybe psionics.
What a cyberpunk world doesn't need:
* Evil megacorporations running everything. It's been done before, and it's trite. Like someone else said, the subtle anti-capitalism message is also a bit annoying.
* Magic, or traditional fantasy-type magic at least. Shadowrun works great but is a genre unto itself. Only Shadowrun can or should be Shadowrun. Anything else that tries to mix fantasy and cyberpunk would just be a bastardization, or be thought of as silly, or both.
* Other species of sentient humanoid life. However, having enhanced primates (chimps or gorillas) or smart dolphins presents interesting possibilities that haven't been fully explored yet (save for "Planet of the Apes" and "SeaQuest").
* Necessarily outrageous aesthetic styles. "Punk" is out. How about a revival of medieval clothing styles? Draw straight from the PHB. Heck, even attribute this trend in-game to the meteoric rebirth of a classic fantasy RPG, now in it's 3rd edition ...
I'm sure there's more to both lists that can be added, but there's my two lists.