There is currently a temporary limit on Tier 1 visa applications made from outside the UK. It is very possible that all out of Country Tier 1 visas for the whole year will be fully used up by January 2011. It is already the case that the monthly allocation of 600 visas is fully used up at the beginning of each month.
If you are already in the UK you do not come under the temporary limit. However, it is important to apply before April 2011. From April 2011 the Tier 1 visa will be replaced or will change into an exceptional talent visa limited to 1,000 visas per year that hardly anyone will qualify for. The permanent immigration cap will also be introduced in April 2011.