let’s say Macintosh provides the iPhone SDK to people who want to make and sell iPhone apps. Android marketplace implies the use of Android platform. But I just cannot seem to figure out what it is that the Google Apps Marketplace is offering the vendors, beyond google authentication and an advertisement spot in their store. Has Google given access to some higher level user interface development framework, such as the one that presumably underlies Gmail or their other Apps? Or are they just trying to profit purely from people making web applications using whatever platform they wish and then serving as advertiser and gate-keeper in sales?
Is there some connection between Google Web Toolkit and Google Apps Marketplace?
(rant)Why is the company run by geeks so freaking dyslexic about what they are offering to other geeks?(/rant)
It does!
There’s the Android Development Kit which makes apps that can run on any Android device, and it can be extended using the Native Development Kit to make apps that are hard specific, but a lot faster. Further things like controling Google apps can be done through the Google APIs
Further there’s theAndroid Market where people can sell and give away Apps.
The Tao’s Revenge, Android platform is great, but that’s just for the Android devices. Whereas Google Apps Marketplace seems to be something else, it’s supposed to be for apps accessible via browser on the desktop. At least that’s my hazy understanding of it.
Google Apps is Google’s hosted webserver product. It allows developers to create and deploy web-based applications built on Google’s infrastructure. As customers create web services for Google Apps, they want a way to sell them – hence the Google Apps Marketplace. If you want to create your own website and don’t want to pay or manage the underlying services, Google Apps is one solution. There are a lot of others, including Amazon’s S3. Here is the wiki describing Google Apps and the Google Apps Marketplace. (All this has nothing to do with Android or their Chrome browser).
Google’s mobile OS, Android, has an SDK/API for app developers to use. Android Apps can be sold via the Android Marketplace. There are alternatives – Amazon just launched an Android Marketplace called Appstore for Android. Mobile carriers such as Verizon Wireless and AT&T also have their own stores. These stores provide a point-of-sale and credit card processing in return for a fee. They also offer varying levels of application verification/authentication.
Google’s web browser, Chrome, and their OS, Chrome, also offer an application store, Chrome Web Store. Here you can buy browser plug-ins, themes, etc.
Google Web Toolkit is unrelated to all of these things; it is independent. IIRC, it allows you to easily add AJAX functionality to your website. If you have a website (hosted on Google Apps or not) and you want to add Java-script AJAX support, then one solution is to use GWT.
Missed the edit window…
Tao mentioned the Google APIs. These allow Android mobile applications to access the data in Google applications (Gmail, Calender, etc – this is different than Google Apps). There are other APIs to do the same thing from web-services as well as from PCs. One example of such an interface is Google Command Line which allows you to write shell scripts on your PC that can access your Google application’s data.
The reason it is confusing is because there are a lot of different products, interfaces, SDKs, etc. It can be overwhelming if you have to learn about them all at once. It is not so bad if you were around when they were released and got to learn about them one-by-one.
CaveMike, thanks for extended reply. Wow, so they have Chrome marketplace too.
Can you explain in simple words what “web services for Google Apps” means? Let’s say I think that their drawing editor application really sucks and I see an enormous market for drawing in the cloud 
- so can I improve on that by making a “service”?
I always thought that services is just a way to split my own web app into several parts that interact using service format. But what does that have to do with Google Apps?
Ugh, I screwed up my earlier reply. I confused Google Apps with Google App Engine.
Google App Engine is the product that allows you to build your own web-apps and host them on Google’s server using their authentication and infrastructure. Alternatively, you could host your own web-server, database, and app using something like LAMP. Or you could use something like Amazon’s S3 for the hosting.
But you didn’t ask about Google App Engine; I just wanted to clarify what I got mixed up.
Google Apps is a service that let’s you create a domain name, a bunch of users, and give each of these users gmail, calendar, gtalk, sites (wiki), groups, and docs (word processor, spreadsheet, slideshow). The users in this domain can share docs, calendars, etc. There are similar products: Google Apps for Business and Google Apps for Education which provide similar services, but with different prices. I should have remembered this because I think we discussed this is another thread.
Google Apps Marketplace is a place to share 3rd-party Google Apps applications. Here is some developer information about writing Google Apps applications. Check out the Overview section for a better explanation than mine.
I don’t know much about Google Apps applications, but it seems it is possible to create a better drawing tool that integrates with Google Apps. I would start here for tutorials and explanations. There are tutorials in 5 different languages. This is a link to the million different APIs that you could use (including GWT).