Liferay is very robust web portal in the market which follows JSR 168 and JSR 286 standards.
Liferay has introduced Liferay Android SDK to develop applications using Liferay portal web service.
Liferay is supporting JSON web service from which we can develop mobile applications.
Liferay have service builder tool for creating web services for liferay applications. We simple call this web service so that we can get dynamic data that we can display in Mobiles Applications. This is very useful when we develop dynamic mobile applications.
Liferay have SOAP and REST supported web services.
If we want used HTML5 Mobile apps for Cross platform then we can Use PhoneGap
PhoneGap is frame work from which we can design mobile apps using HTML5 and Java Script. These applications can run in any mobile platforms.
This phone gap provide flexibility to create Mobile Application for any mobile platform like Android, iOS, Black Berry and Firefox Mobile OS
We can use Ajax in HTML5 to consume Restful web services.
We already have very rich java script libraries for Ajax like Jquery, DOJO, YUI and AUI.
In any application only one thing is consuming web services.
The following is location where we can get more information about PhoneGap
The following is location you can get Liferay Android SDK and Sample Application
The following is Liferay Android Tutorial
The following is create web services and using liferay web services in other platforms