SQL - INFORMATION_SCHEMA for All Databases On Server

Expanding Dalex's answer into code.

--Make sure you have a global temporary table to use. Double dots are shorthand for .dbo.
IF OBJECT_ID('tempdb..##test') IS NOT NULL DROP TABLE ##test
--Create the table definition the easy way.
SELECT * INTO ##test
FROM ???.INFORMATION_SCHEMA.TABLES --The ??? will be whatever the name of your first database is.
DELETE FROM ##test
--Add all the data.
EXEC sp_MSforeachdb 'USE ? INSERT INTO ##test SELECT * FROM INFORMATION_SCHEMA.TABLES'
--View all the data.
SELECT * FROM ##test
--Clean up.
DROP TABLE ##test

Modified Dustin's code (from Dalex's suggestion) to accommodate database names with spaces and eliminate common system tables from results.

--Make sure you have a global temporary table to use. Double dots are shorthand for .dbo.
IF OBJECT_ID('tempdb..##test') IS NOT NULL DROP TABLE ##test

--Create the table definition the easy way.
SELECT top 1 * INTO ##test
FROM INFORMATION_SCHEMA.TABLES
DELETE FROM ##test

--Add all the data.
EXEC sp_MSforeachdb 'USE [?] INSERT INTO ##test SELECT * FROM INFORMATION_SCHEMA.TABLES'

--View all the data.
SELECT * FROM ##test
WHERE TABLE_CATALOG NOT IN ('master','tempdb', 'msdb')
ORDER BY TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME

--Clean up.
DROP TABLE ##test

You can do this only by using dynamic query for database iteration. One way is using ms_ForEachDB stored procedure, second is querying sys.databases dynamic view.