Android 2.3.1 Gingerbread has been released for iPhone 3G, 2G and iPod touch (1st-gen). This is a preview release and therefore it is not distributed via popular Android installer package called Bootlace. Therefore, downloading the binaries will be required and you will have to install it manually using the instructions given in the video below.
Post Update (Recent Release Summary)
2.3 Gingerbread refined the user interface, along with an improved soft keyboard and copy/paste functionality. It also improved gaming performance, SIP support (VoIP calls), and included support for Near Field Communication.
3.0 Honeycomb was a tablet-oriented release which supported larger screen devices and introduced many new user interface features. It supported multi core processors and provided hardware acceleration for graphics.
3.1 Honeycomb was announced at the 2011 Google I/O on 10 May 2011. It focused on allowing Honeycomb devices to directly transfer content from a USB device.
3.2 Honeycomb released at July 15 2011, is an incremental release that adds new capabilities for users and developers, such as optimization for a broader range of screen sizes, new “zoom-to-fill” screen compatibility mode, an extended screen support API and the capability to load media files directly from an SD card.
Ice Cream Sandwich: has now been released. Many forked versions of ICS are also running on a number of tablets and mobile phone devices.