It appears that Google has accidentally confirmed Android 4.3 software prior to the start of the Google I/O conference.
According to The Verge, Android 4.3 was seen in a search listing on Google's developer website. No indication was given on whether or not the new software would come with a Jelly Bean title, though it is suspected that this will be the case. Android 4.3 sightings in server logs have shown that the build numbers associated with Android 4.3 all start with J. This has been the case for every other Jelly Bean ROM.
Rumors about Android 4.3 have been swirling for weeks and it appears that we will in fact be seeing that instead of Android 5.0. Rumored features for Android 4.3 include support for Bluetooth Low Energy and OpenGL for Embedded Systems 3.0 graphic specification. You can also likely expect to see Google Play Games, which is a more advanced version of the iOS Game Center. Users may be able to play real-time multiplayer games and other games with connected players. Cloud based saving is also believed to be featured.
More will be known once the new software is officially unveiled at Google I/O. You can watch the event live here.
Other rumored announcements at Google I/O include a new Nexus 7 tablet, which some are calling the Nexus 7.2. The tablet is rumored to have a seven-inch 1920x1200 HD display, run Android 4.3 and have thinner bezels like the iPad Mini. You might also see a 32GB White Nexus 4 LTE.