Back in early 2007 Netherlands-based Nimbuzz launched a beta for its free application which supported voice, presence, and SMS. TechCrunch UK reports that Tuesday will see it aim squarely at mobile handsets and social networks, launching with Java and Symbian client software which will work across an impressive 500 handsets. This will allow users to make and receive calls across 50 countries, particularly emerging markets where PCs are just too expensive for most people. (An iPhone client is under development). Nimbuzz will offer free mobile VoIP, conference calling, IM and group chat and photo and file sending across multiple IM communities, including Skype, MSN, Google Talk, Yahoo!, AIM, Jabber and ICQ, plus 23 social networks, including apps/widgets for Facebook and Myspace, which are key to its distribution strategy.

Founded by two Dutch mobile veterans Evert Jaap Lugt (formerley KPN) and Martin Smink, Nimbuzz was most recently funded to the tune of $10 million by Mangrove Capital Partners (the original Skype investor) and says it already has 500,000 registered users since the beta launched last year.

Over the past two years about a dozen startups have started to offer IM to VoIP over mobile to take advantage of the increase in flat-rate data plans. They include Mig33 (which also offers IM photo sharing, VoIP and social networking features), Fring and Truphone, among others.

Update: So feedback from users is that the download is way too big, like 1MB, which is way too heavy for a mobile app.