Right now, Microsoft have their BETA Antispyware to download for free. Then when its' tweak, tuned and have found all the bugs which will have been reported by users, they will come out with an official version.
Internet Explorer 5.5 was at a time in a beta stage. As a matter of fact Windows 95 which came out in version A, B, C, to Windows 98 and finally Windows 98SE (second edition) were more or less betas leading to Windows 98SE which should have been an actual Windows 95 that didn't come right on time.