Skype for mobile has already hit the 5 million downloads mark since April 2004, so this week's release of the public beta of version 2.2 should already have a loyal following.

So is it worth upgrading? Well, there are certainly some neat new features.

Top of the pile on a purely practical level is that the range of supported Windows Smartphone and Pocket PC-powered phones has more than doubled from the previous version, and the app now works on over 120 Windows-powered mobile phones and PDAs.

Also, the general Skype look and feel has been well and truly polished up. Perhaps however the most notable new feature of the app itself is the enhanced support for the 'Today' or home screen. Right from the home screen on 2.2 you can see your Skype status, call and chat log and voicemail alerts. This integrates Skype much more tightly with other messaging options on the phone such as SMS, MMS, email and, of course, voice calls, and also adds one-touch access to Skype. The overall aim seems to be to make the process of making a Skype call as intuitive and easy as making a regular phone call from your mobile.

There are a number of other interesting touches too, such as being able to take a photo and directly upload it as your Avatar; handy if you want to keep your office-bound Skype buddies abreast of your tan progress whilst on vacation. Multi-person chats are also supported.

All-in-all Skype has come a long way on mobile since I downloaded the first, text chat-only version of the client on my C500 phone way back (!) in April 2004. This new release does have pretty much all of the core feature set of Skype and in my opinion cramming any more features into the client at this juncture would have been unwise based on the limited form factor that mobile offers. Now roll on all those broadband-speed HSDPA Windows Mobile phones we've been promised for Q1 next year, and of course the Windows Mobile phone made of marzipan.

Skype for Windows Mobile can be downloaded for free at http://skype.com/go/mobile. For a great roundup of the good, the bad, and the ugly Windows-powered phones you can use for Skype, check out top Microsoft Mobile sites Pocket PC Thoughts, Modaco.com, Engadget Mobile and Coolsmartphone.com.