From 6 April 2010 and onwards, significant changes are going to apply for Tier 1 and Tier 2 applicants. I would say almost the majority of new applicants will be able to get their immigration visas after that.

You could simply draw the same conclusion from the two points table:

Before 6 April 2010:

6 April 2010 and onwards:

For those current migrants who are already in the UK in Tier 1 or its predecessors, there are some transitional arrangements available. The new points table will not apply for them and the original one is still valid. The categories are:
    • Tier 1 (General), with leave granted before 6 April 2010
    • The Highly Skilled Migrant Programme (HSMP)
    • Writers, Composers and Artists
    • Self-employed Lawyers

If anyone is still able to make the application before 6 April 2010, please do hurry up so you could take the advantages of the old rules.

PS: More information can be found on the UK Border Agency. Here is the link:
http://www.ukba.homeoffice.gov.uk/sitecontent/newsarticles/2010/255022/46-new-rules-for-t1-t2-and-ir
Statement of policy – changes to Tier 1 and 2 of the points-based system