By now, news of Apple's invitation to a specifically iPhone-related event, on Tuesday at its Cupertino campus in California has become old. However, it is still unclear whether this event will see the release of the highly-anticipated iPhone5.

In fact, a Wall Street analyst has speculated that Apple could release two phones - the iPhone5 and a cheaper version of the iPhone4, the iPhone4S - at the event.

Specifically, we expect an iPhone5 with aluminum uni-body construction, better camera and slightly larger screen size as well as a cost-down iPhone4 or iPhone4S, Deutsche Bank analyst Chris Whitmore wrote, in a note to clients.

Other points of speculation include the pricing of the models, with discussions on the possibility of a cheaper iPhone fitting into Apple's global strategy having flourished.

The iPhone5 is expected to run on the latest iOS 5, which will be coming with 200 new features, including an improved notifications system, Newsstand and iMessage. In addition to this, the iPhone5 is expected to feature the new iCloud service to help operate iTunes wirelessly.

However, this time the iPhone seems to have a number of competitors, all of whom may give the company a run for its money.

Let's take a look at some of these.

Samsung Galaxy S2

The Samsung Galaxy S2 continues its strong march forward in the smartphone wars, providing stiff competition to Apple's iPhone4 and could prove to be a handful to the forthcoming iPhone5.

The device, which was recently launched in the United States, sold a whopping 10 million units since its launch in late April 2011; a figure, which even exclusive of sales from the U.S., which is believed to be the largest market for smartphones. On the other hand, Apple sold 20 million iPhones in the third quarter.

The figures, though indicative of a gap in terms of absolute numbers, between the Galaxy S2 and the iPhone, do seem to imply that Samsung could well be Apple's toughest rival.

The Galaxy S2, which runs on the Android 2.3 Gingerbread OS and sports Samsung's TouchWiz UI, comes with an 8-megapixel camera with flash and can record HD video in 1080p. The phone also has a front-facing 2-megapixel camera for video chat. The phone comes with a choice of 16/32GB of internal memory, with 1GB RAM.

Motorola Droid Bionic

Motorola released its Droid Bionic smartphone on Verizon's networks on Sept. 8. The device runs the Android Gingerbread 2.3.4 OS and is powered by dual-core 1 GHz processors, 1 GB of RAM and a stunning 4.3-inch qHD display, with a resolution of 960x540-pixels.

The Droid Bionic sports an 8 megapixel auto-focus camera with flash and 1080p HD video capture, as well as a front-facing camera for video chat over 4G LTE, 3G or Wi-Fi. The phone has 16GB of internal storage and a pre-installed 16GB MicroSD card, which can be expanded to 32GB.

Verizon offers the Droid Bionic at $299 with 2-year contract.

Google Nexus S 4G

Rumors that Google's update of the Android OS - nicknamed Ice Cream Sandwich - and to be launched on a new Samsung smartphone, to be called Nexus Prime have been around for a month now. The phone is touted to be an absolute beast and is expected to feature a 1.5GHz Snapdragon chip along with a monster-sized display sans the menu buttons that are usually found in Android devices.

It will have a 5-megapixel rear-facing camera that will deliver superior low-light performance and will also feature a 1-megapixel front-facing camera. The Nexus 4G will offer 1080p video capture and playback capability. It is further rumored that the Nexus 4G will feature a 4G LTE radio and 1GB of RAM. The phone is not expected to be released before November.

Motorola Droid HD

An unofficial Android-based device from the Motorola camp, under the moniker Droid HD, showed up alongside the Droid Bionic in leaked pictures posted by a tipster. The photographs were posted by Endgadget on its Web site.

The snapshot suggests that the Droid HD could be much thinner than the Droid Bionic and it is believed that the HD will bring the goodness of Gingerbread on a 4.5-inch display, with a resolution of 1280x720. The phone is also expected to sport an 8-megapixel camera capable of shooting videos in 1080p.

The snapshots also suggest that the phone has a SIM slot and a MicroSD slot on the left side, with a volume control and power button on the right.

Endgadget speculated that the phone could be between 8.5 and 9mm thick. The rumors also suggested that it would feature a Texas Instruments' OMAP processor, 1GB RAM and a screen larger than the Bionic.

HTC Vigor

HTC is rumored to be considering the launch of another Android Gingerbread-based smartphone, titled HTC Vigor. The speculation is that the Vigor will sport a 1.5GHz dual-core processor.

The phone, which is touted to be a replacement for the HTC Thunderbolt, is expected to have a 4.3-inch display with 1280x720 screen resolution.

The Vigor could be fitted with an 8-megapixel camera and is expected to offer 1GB RAM, 16GB internal storage and the Beats Electronics Technology - best known for the high-performance line of headphones backed by hip-hop artist /producer Dr. Dre.