Cloud Computing vs Grid Computing

2009-2010 has been the year for new computing technology i.e Cloud Computing, as was the year 2007-2008 for SaaS-(Software as a Service). Cloud & grid Computing maybe considered opposites in terms of Functioning.Cloud Computing Assimilates everything into one place whereas GridComputing Divides everything.
So for those who wanna know here's a brief overview:
Cloud computing is based on the principle of letting others do the work for you, technically it means running all your Apps, documents & data from a third party server.
Now, the question that people may ask is that, this have been done from long time & is nothing new, we have been using Apps from the net & storing our data online, So whats NEW?
Well the ans is, that cloud computing not only stores our data online & provides us with Apps, but it also does the processing for us. The online apps that we used before, used local processing upto some extend, But a cloud provides its own processing.
Now, from individual point of view this may not be of much significance, But for Large Organizations, which have huge data networks, Cloud is a boon, in a way that it saves them with the hassles of maintainence, s/w & h/w update & other hardware costs(as it doesnt rely on Host h/w or s/w), plus it saves time of the IT folks & helps them to deal with WHAT then to think about HOW.
Many may have concerns with security related issues that cloud computing may pose, coz for Corporations it amasses to huge amount of confidential & important data & it can be said that a Cloud is as safe as your email or any online account.
Many companies Like IBM, MICROSOFT & GOOGLE provide cloud based services.There have been a lot of buzz of different possibilities & different experiments with cloud platform, for example European Union is carrying out research studies on the possibility of providing Cloud based Gaming & other ON-DEMAND services.

GridComputing on the other hand is something exact opposite, cloud does the processing for you, Grid needs processing from you. Grid computing has mostly used by scientific & research based Organizations & Universities round the world.
Its based on the CLIENT-SERVER model. In a Grid there are several thousand (may be more) computers connected as nodes to a central server(maybe more than one server). The processing of data such as scientific analysis or Disease based research, is divided & distributed over the nodes. The node provides the processing power, while the server just distributes, assimilates & administers the process.
A single Grid can provide computing power Equivalent to a SUPER Computer, For example THE WORLD COMMUNITY GRID, which researches on cures for Diseases such as Cancer, Aids etc has 475,000 registered user &  Computing power equal to approx 3.3 teraflops.
Concept of Grid Computing has also been used in the underground world for stealing data & spreading malware, The Zeus Botnet, The Torpig Botnet are similar to concepts of grid computing, though not entirely similar.