still gets virus updates and works fine on Win98. In fact, I just renewed my free license and it is good 'til July 1, 2012. Of course, the virus updates may not continue that long. It appears that Avast has some paid commercial users still running Win98 who can't easily or economically upgrade to newer OS's, so they are continuing the virus updates for now. This is good news for the free users, too.
Sure, this will eventually come to an end. Currently, BitDefender 8 and ClamWin are the only two other free AV programs I know of that still support Win98, but both are demand scanners only and provide no real time protection.
But, there's still hope with ClamWin. A dedicated Win98 user has developed a program called Clam Sentinel which acts as a real time front end for ClamWin, and has additional heuristic capabilities which increase malware detection by as much as 60-70%. Rumor has it that ClamWin 1.x will include Clam Sentinel for it's real time scanning/protection. Time will tell.
Preparing for the future, I am already running all three: Avast and ClamWin with Clam Sentinel integrated. Yes, these two real time AVs can coexist with a few simple modifications. If anyone is interested in details, please ask.