Just spoke to the Sales team at Three, and was looking for a Sim only plan and asked for a plan that has more than 500 minutes and alot of texts. He told me they are bringing this new on which gives:
Free messenger, skype, facebook, twitter etc
For £20 on a 30 day rolling plan or £15 on a 12 month contract.
HOWEVER: This does NOT include free 3-3 minutes for some reason.
This is an alternative to the T-mobile or O2 offers which are about and would be good if you get 3G coverage.
Said the stores MAY be offering but still unsure. Best to order over the phone.